Theta Ophiuchi is a Class B2

Stellar classification

In astronomy, stellar classification is a classification of stars based on their spectral characteristics. The spectral class of a star is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are most prominent in the light, giving an objective measure...

, third-magnitude star

Star

A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...

 in the constellation

Constellation

In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....

 Ophiuchus.
It lies on the "right foot" of the serpent-bearer, and is only a little to the southwest of the Kepler's Star, the nova of 1604.

Theta Ophiuchi is a variable star

Variable star

A star is classified as variable if its apparent magnitude as seen from Earth changes over time, whether the changes are due to variations in the star's actual luminosity, or to variations in the amount of the star's light that is blocked from reaching Earth...

 of the Beta Cephei type

Beta Cephei variable

Beta Cephei variables are variable stars which exhibit variations in their brightness due to pulsations of the stars' surfaces. The point of maximum brightness roughly corresponds to the maximum contraction of the star. Typically, Beta Cephei variables change in brightness by 0.01 to 0.3...

, with a short period of just 3h 22m.
It is located about 565 light-year

Light-year

A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...

s from Earth

Earth

Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

.

According to R.H.Allen's, Star Names: Their Lore and Meaning

Star Names: Their Lore and Meaning

Star Names: Their Lore and Meaning is a book by Richard Hinckley Allen, published in 1899.It discusses the names of stars and constellations and their origin.-Author:...

(1899), θ Oph together with ξ Oph formed the Sogdian Wajrik "the Magician", the Khorasmian Markhashik "the Serpent-bitten" and with η Oph the Coptic Tshiō, "the Snake", and Aggia, "the Magician".