Theodore Seio Chihara was an American mathematician working on orthogonal polynomials who introduced Al-Salam–Chihara polynomials, Brenke–Chihara polynomials, and Chihara–Ismail polynomials. His brother was composer Paul Chihara. He earned his PhD from Purdue University, where his thesis advisor was Arthur Rosenthal. Chihara died on February 11, 2026, at the age of 96.