Harry Chapman Thayer (December 31, 1873 – August 4, 1936) was an All-American football player and broker.

Thayer then attended the University of Pennsylvania where he played at the halfback and fullback positions for the Penn Quakers football teams in 1891 to 1892.

[1] At the end of the 1892 season, Thayer was selected by both Walter Camp and Caspar Whitney as a first-team halfback on the 1892 All-America college football team.

[2][3] Thayer later worked as a broker associated with the brokerage firms of West and Co and, later, Montgomery, Scott and Co.

[4] He gained fame as the leader of a campaign to eliminate "bucket shops" from the brokerage business.