The Animals

• Martha: The main protagonist, Martha is a talking dog that was born a stray and was put in the dog pound as a puppy. Martha also had a lot of energy as a puppy. Not much else is known about her past, but in one episode she explains that before Helen adopted her that a pair of bumbling thieves (now revealed to be young Otis Weaselgraft and Bumblecrumb) changed her name to Pablum and tried to use her for crimes, but in the end she got them arrested and returned to the shelter, where Helen's family adopted her. Martha gained the ability to talk after eating alphabet soup; the letters in the soup went to her brain instead of her stomach, which was an event that couldn't be repeated with another dog, but Martha has to continue eating it to retain her ability to speak. In one episode opening the can from the bottom caused Martha to speak backwards. Martha often sticks her nose in other people's business, trying to help, but sometimes accidentally causes trouble. In the episode "Truman and the Deep Blue Sea" it is revealed that she got carsick when she was a puppy. She has had jobs as a telemarketer, a radio talk show host, firedog, etc. In the episode "Martha's Pickle" she mentioned that she still does her radio show in the episode "Martha Gives Advice". Despite her talk show, various community members seem surprised when Martha talks to them, or skeptical when someone mentions a talking dog. Martha also has a superhero personality called "Mighty Mutt" and sometimes "Super Pooch". It is revealed that Martha is a mutt
  Mixed-breed dog
  A mixed-breed dog, also known as a mutt or mongrel, is a dog whose ancestry is generally unknown and that has characteristics of two or more types of breeds. A mixed-breed may be a cross-breed dog, a random-bred dog, or a descendant of feral or pariah dog populations...
  
  . Martha is voiced by Tabitha St. Germain
  Tabitha St. Germain
  Tabitha St. Germain is a Canadian stage actress. She has made the transition from stage work to voice work, and has since become one of the core female voice actresses working with Ocean Productions in Vancouver, British Columbia, Canada.- Anime :* .hack//Roots - Asta, Nazo Grunty* Black Lagoon -...
  
  
• Skits: Helen's other dog, who tried the same alphabet soup, but it did not make him talk. Skits was first introduced in the episode "Martha and Skits". Skits also has a history of misbehavior that started in the episode "Martha Runs Away" and ends in the episode "Skits Behaves". Skits has also been shown to be heroic, getting the fire department to help get Martha down from a tree in the episode "Martha to the Rescue". He also has brontophobia. He is also Windy McCloud's weather dog .
• Nelson: Ronald's cat, and Martha's nemesis.
• Polly: Ronald's parrot.
• Bob: A mean dog who appeared in the episodes "Martha Walks The Dog", "Martha Doesn't Speak Monkey", "Nurse Martha", and "What's Bothering Bob?" He also plays with his food and eats his toys.
• Courageous Collie Carlo: Star of a fictional TV series on the show, and whom Martha has a crush on. Carlo first appeared in "Martha to the Rescue". He has a fear of flowers, "anthophobia", obtained after an embarrassing accident in his studio.
• François: Mrs. Clusky's snobby white poodle.
• Big Minnie: A monster that was seen in the episode "Martha Camps Out" and mentioned in the episode "Martha and Truman Get Lost", where she finds Truman's missing lucky rock.
• Jeffey: An elephant that lives at the zoo and is a recurring character on the show.
• Professor Monkey: A monkey writing books. Professor Monkey knows how to understand all languages, however, only knows how to speak monkey. He knows how to play the guitar.
• Kitten: A little orange kitten that lived with the Boxwoods for a short period of time waiting to be adopted. It appears in the episodes "There Goes the Neighborhood" and "Martha Acts Up" and took an instant liking to Martha; saying that she reminded him of his mother. At first Martha and Skits both despised the kitten being prejudice of his species and thinking that all cats are bad. But at the end Martha and Skits befriend the kitten and learn their lesson about not to judge someone's personality based on what animal they happen to be. While he was adopted by another family, Martha and Skits are allowed to visit him whenever they want.

The Kids

• Helen Lorraine: Martha's owner who has red, short, and curly hair. She is ten years old and she is also Skits' owner. She is usually the voice of reason on the show. Helen also is the closest to Martha and thinks of Martha as her best friend. Out of the four main kids, Helen is the most sensible. Despite this, she can be a bit overbearing and even show her mean side (as in "Martha Runs Away", where she scolded Martha for things she didn't do.) Her best friends are T.D. Kennelly, Alice Boxwood, and Truman Oatley. Helen is closely linked to Arthur from the TV show of the same name. Voiced by Madeleine Peters
  Madeleine Peters
  Madeleine Heeps is an American child actress who provides the voice of Helen Lorraine in the PBS Kids children's television series Martha Speaks. She also provides the voice of Scootaloo in the children's TV series, My Little Pony: Friendship is Magic. She is now in 10th grade, and is 15 years...
  
  .
• T.D. Kennelly: Helen's best friend. T.D. is a fan of Professor Monkey. His father, O.G., is an inventor, while his mother is the vice-principal at his school. T.D.'s academic performance is quite underwhelming. He has admitted that every minute in school feels eternal. He also believes in the supernatural. He has a uncle named C.K. T.D has an older sister but because she's at college
  College
  A college is an educational institution or a constituent part of an educational institution. Usage varies in English-speaking nations...
  
   he never sees her. He has a cousin named C.D. T.D. is closely linked to Buster from Arthur because he is voiced by Alex Ferris
  Alex Ferris
  Alexander "Alex" Ferris is a Canadian child actor. He currently stars on jPod as Connor Lefkowitz, and appeared in The Time Traveler's Wife as Young Henry DeTamble.Ferris was born in Vancouver, British Columbia, Canada...
  
  .
• Alice Boxwood: Helen's best school friend. She is a tomboy, and she wears glasses. Alice can be somewhat mean-spirited, as seen in "Ice Scream" and "Martha Puts Out The Lights". She has ill-luck with her birthdays and is generally clumsy. Alice is closely linked to Francine from Arthur. She is voiced by Christina Crivici in seasons one through three, and was then replaced in season four by Michelle Creber.
• Ronald "Ronnie" Boxwood: Alice's big brother who's in high school. He hates Martha, and he has a cat named Nelson and a parrot named Polly. He is something of a snob who likes to scare people. Ronald is closely linked to Binky from Arthur. He is voiced by Kathleen Barr
  Kathleen Barr
  Kathleen Barr is a Canadian voice actress. She is also the sister of Professor Mark Lyle Barr at Saint Mary's University in Halifax, Nova Scotia.-Filmography:...
  
  .
• Jake Lorraine: Helen's two-year-old baby brother. Martha calls him "Jakey", and loves to teach him how to talk.
• Carolina: Helen's cousin, who is eleven years old. She is very fashion-conscious and sings horribly. She is usually portrayed as a know-it-all, although she cares for Helen very much. Her father and Helen's mother are siblings. She often uses Spanish
  Spanish language
  Spanish , also known as Castilian , is a Romance language in the Ibero-Romance group that evolved from several languages and dialects in central-northern Iberia around the 9th century and gradually spread with the expansion of the Kingdom of Castile into central and southern Iberia during the...
  
   words and phrases, giving the translation shortly afterwards. Carolina is closely linked to Muffy from Arthur. Voiced by Vanesa Tomasino.
• Tiffany Blatsky: Carolina's friend from France. She is shown to be obsessed with winning everything.
• Truman Oatley: Helen's African-American friend that loves reading and is prone to seasickness. He lacks confidence in many things and is reluctant to try because he is convinced it is frequently pointless. He also has entomophobia
  Entomophobia
  Entomophobia is a common fear of or aversion to insects and similar arthropods, and even other terrestrial invertebrate animals, such as worms. Commonly, this condition might be referred to as the "fear of insects or bugs". This condition causes a slight to severe emotional reaction, a form of...
  
  . Truman is closely linked to Brain from Arthur. Voiced by Cedric Payne
  Cedric Payne
  Cedric Payne is a Canadian voice actor that provides the voice of Truman on the television series Martha Speaks. He also voices Petey the Peteinosaurus, one of the few characters that is not a dinosaur, on the show Dinosaur Train.- References :...
  
  .
• Milo Lee: Skits's seven-years-old friend. He likes dogs very much.. He appeared in Skits and Mr. Scruffles, Carolina Picks a Lily, T.D.’s Magic, Wagstaff Races and cameo in Alice Covers Up.
• C.D. Kennelly - T.D. four-years-old cousin. He is Doggie Lover, but Skits likes him. He appeared in Martha and the Doggie Lover, T.D.’s Magic and cameo in Wagstaff Races.

The Adults

• Mariela Lorraine: Helen's mom, she works in a flower shop. She is Hispanic
  Hispanic
  Hispanic is a term that originally denoted a relationship to Hispania, which is to say the Iberian Peninsula: Andorra, Gibraltar, Portugal and Spain. During the Modern Era, Hispanic sometimes takes on a more limited meaning, particularly in the United States, where the term means a person of ...
  
  .
• Daniel "Danny" Lorraine: Helen's dad who works as a bus driver. He is Caucasian
  White people
  White people is a term which usually refers to human beings characterized, at least in part, by the light pigmentation of their skin...
  
  .
• Otis Weaselgraft: One of the antagonists of the TV series, who wants to dognap Martha so they can make money off her special ability, and calls Martha "that talking dog", but is constantly thwarted by Martha and her young friends. His main downfall is he underestimates Martha's intelligence. In one episode, he sold T.D. a "steak tree" as a scam, but even though the main characters discovered it didn't grow steaks, he wasn't caught. He and Pablum are recurring antagonists in the series, despite repeatedly getting caught and defeated in his scams by Martha. Both he and Pablum always manage to escape arrest.
• Pablum: A scientist who often teams up with Otis Weaselgraft, an antagonist of the TV series. Despite trying his best to help Otis, he is constantly abused by him.
• Granny Florence "Flo": Owner of the factory which makes the Alphabet Soup Martha needs to speak. She is shown to be greedy and regrets having to put "every letter in every can" (per the company's slogan).
• Granny Elsie: The founder of Martha's alphabet soup.
• Alfred "Al" Abbott: The alphabetician who makes the letter A for the alphabet soup Martha eats. He is laid off when Granny Flo decides to cut costs by getting rid of half the letters for the soup, but gets it back after he shares his last can of complete alphabet soup with Martha, who scares Granny Flo into giving everyone back their jobs. He is voiced by Samuel Vincent
  Samuel Vincent
  Samuel Vincent is a Canadian voice actor who works with the Ocean Productions based in Vancouver, British Columbia, Canada. He was born in North Vancouver, British Columbia.-Biography:...
  
  .
• Kazuo: The dog pound owner. He wants to make sure all the dogs at the pound get good homes and ends up adopting Pops, one of the longtime residents at the pound. While working,he wears earmuffs with a radio. He is initially voiced by Matt Hill
  Matt Hill
  Matthew "Matt" Hill is a Canadian voice actor. He is known for several roles, including Kevin Keene/Captain N in Captain N: The Game Master, Kira Yamato in Gundam Seed and Gundam Seed Destiny, Ed in Ed, Edd n Eddy, Raphael in Ninja Turtles: The Next Mutation, Ryo Sanada in Ronin Warriors and Artha...
  
  , and later by a different uncredited actor.
• O.G. Kennelly: T.D.'s dad. He owns a workshop and is shown to be quite eccentric and enjoys inventing things. He is voiced by Terry Klassen
  Terry Klassen
  Terry Klassen is a Canadian voice actor and voice director in Vancouver, British Columbia. He co-created Yvon of the Yukon. He is the voice director for shows including Martha Speaks, "Johnny Test", "George of the Jungle", "Ed, Edd n Eddy", several "Barbie" movies, "Transformers", "CardCaptors",...
  
  .
• Janice Kennelly: T.D.'s mother. She is the vice-principal of the school.
• Mrs. Eulah Demson: Helen's neighbor and the neighborhood grouch. She is highly opinionated, very proud, conniving, and often intolerant of others' activities. She can barely stand Martha, however, it has been shown that she secretly likes Martha. She has loud alarms on her front porch that go off when someone rings her doorbell. She has a young granddaughter named Felicity that appears in season four that is a mute
  Mute
  Mute may refer to:* Muteness, a speech disorder in which a person lacks the ability to speak* Mute, a silent letter in phonology* Mute , an upcoming sequel to the movie Moon...
  
   and is very timid of Mrs. Demson.
• CK: TD's uncle. He's a farmer who Helen, Timmy. David., and Martha once visited. His farm is seen in the episode "Down on the Farm" and was mentioned in the episode "Skits Behaves".
• Louie Kablooie: A person who attempts to rob Aprin Jewelers.
• James "Jimmy" Gimmie: Louie Kablooie's accomplice in the episode "Codename: Martha".
• Karl: The person who owns the butcher shop.
• Mrs. Clusky: Helen's teacher; she does not allow dogs in the school.
• Cisco: A Russian old man.
• Lucy "Lucille" Lorraine: Daniel's mom. She doesn't like bacon, and she is allergic to flowers.
• Bernard "Bernie" Lorraine: Daniel's father. He once lost Lucille's keys, bended her skies, and sold Lucille's chair for a big grizzly bear.
• Boomer: An old man with fading sight, often losing his glasses.
• Mrs. Parkington: An old lady who believes in the ghost of her Great Aunt Martha.
• Windy McCloud: Wagstaff City's meteorologist.
• Mrs. Oatley: Truman's mom. She owns a day care center run at home.
• Mr. Oatley: Truman's dad.
• Brunhilde: An opera singing woman best for singing high notes.
• Terrence Lee: Milo's father.

Dogs in the Pound

• Miranda: A Yorkie poodle
  Yorkshire Terrier
  The Yorkshire Terrier is a small dog breed of terrier type, developed in the 19th century in the county of Yorkshire, England to catch rats in clothing mills. The defining features of the breed are its size, to , and its silky blue and tan coat...
  
  .
• Pops: A mean looking junkyard dog. He was later adopted by Kazuo.
• The Puppy Triplets: Butterscotch, Streak, and Mandarin. Butterscotch was shown in Nurse Martha. Streak, Butterscotch, and Mandarin were adopted by triplets revealed to be Mrs. Clusky's nieces. They were abandoned as puppies, according to Martha .
• Estelle : A white poodle.
• Wally: An English Hound
  English Foxhound
  The English Foxhound is one of the four foxhound breeds of dog. They are scent hounds, bred to hunt foxes by scent.-Appearance:The English Foxhound is about 21-25 inches tall to the withers, and weighs anywhere between 65-75 pounds, although some English Foxhounds bred for the show ring can be...
  
  .
• Bert: A small dog often used by Otis W. to make money.