Clarence Henry Geist (1866 – June 12, 1938) was an American financier who played an important role in the early history of Boca Raton, Florida.

When he was 18 he left Indiana and spent five years in the far West working in cattle ranching, but returned East when he realized he "could not make money where there wasn't any".

[3] Geist then set himself up as a natural gas distributor, where he supplied gas to Blue Island, Morgan Park, then a suburb of Chicago, and Illinois suburbs south of Blue Island that included Harvey and Chicago Heights.

[7][8]: 173  He commissioned the New York architectural firm Schultze and Weaver to create an addition to the 100-room Cloister Inn, resulting in the 450-room Boca Raton Club, which accepted its first guests in December, 1929, ahead of its 1930 formal opening.

He also paid for an elegant, Mediterranean-style depot on the Florida East Coast Railway (in 2017 operated by the Boca Raton Historical Society as a museum).

Geist allegedly bought stock in the railroad in order to influence its choice of Boca Raton depot.