Theodore P. Gilman was an American banker and politician.
He was the son of Winthrop Sargent Gilman

Winthrop Sargent Gilman

Winthrop Sargent Gilman was head of the banking house of Gilman, Son & Co. in New York City.-Biography:He was born in Marietta, Ohio to merchant Benjamin Ives Gilman and Hannah Gilman...

 and Abia Swift Lippincott Gilman. He graduated from Williams College

Williams College

Williams College is a private liberal arts college located in Williamstown, Massachusetts, United States. It was established in 1793 with funds from the estate of Ephraim Williams. Originally a men's college, Williams became co-educational in 1970. Fraternities were also phased out during this...

 in 1862, where he was a member of The Kappa Alpha Society

Kappa Alpha Society

The Kappa Alpha Society , founded in 1825, was the progenitor of the modern fraternity system in North America. It was the first of the fraternities which would eventually become known as the Union Triad...

, and graduated A.M.

Master of Arts (postgraduate)

A Master of Arts from the Latin Magister Artium, is a type of Master's degree awarded by universities in many countries. The M.A. is usually contrasted with the M.S. or M.Sc. degrees...

 in 1865. He married Elizabeth Drinker Paxson (ca. 1843-1912), and their son was Theodore P. Gilman, Jr. (b. 1873).

Gilman entered a banking career, and in the 1870s was involved in financing midwestern railroads; notably, the Quincy, Missouri & Pacific RR.