Theron Ephron Catlin (May 16, 1878 – March 19, 1960) was a U.S. Representative from Missouri's 11th congressional district.

He presented credentials as a Republican Member-elect to the Sixty-second Congress and served from March 4, 1911, to August 12, 1912.

Though he claimed ignorance of the spending, Congress decided he was in violation and he was deemed ineligible for office.

They also found evidence of fraud and when the fraudulent votes were eliminated, that Catlin had lost to Gill.

He resumed the practice of law, and served as a member of the board of directors of St. Louis Union Trust Co.