William E. Glyn was an American

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 male tennis

Tennis

Tennis is a sport usually played between two players or between two teams of two players each . Each player uses a racket that is strung to strike a hollow rubber ball covered with felt over a net into the opponent's court. Tennis is an Olympic sport and is played at all levels of society at all...

 player.

William Glyn from the Staten Island Cricket and B.B. Club was a finalist in the first U.S. National Championships

U.S. Open (tennis)

The US Open, formally the United States Open Tennis Championships, is a hardcourt tennis tournament which is the modern iteration of one of the oldest tennis championships in the world, the U.S. National Championship, which for men's singles was first contested in 1881...

 held in 1881 at the Newport Lawn Tennis Club in Newport, Rhode Island. En route to the final, he defeated Mr. Rives, 1-6, 6-1, 6-1; R.F. Conover, 6-5, 6-2; W. Gammell, Jr., 6-3, 3-6, 6-4 and finally T. A. Shaw, 6-2, 6-2. In the final he met and was defeated by Richard D. Sears 6-0, 6-3, 6-2.

Finals (1)

Year	Championship	Opponent in Final	Score in Final
1881	U.S. Championships U.S. Open (tennis) The US Open, formally the United States Open Tennis Championships, is a hardcourt tennis tournament which is the modern iteration of one of the oldest tennis championships in the world, the U.S. National Championship, which for men's singles was first contested in 1881...	Richard D. Sears	0-6, 3-6, 2-6

Sources