According to The Associated Press:
Mr. Poston, who was married to Suzanne Pleshette of "The Bob Newhart Show," died Monday night at home after a brief illness, a family representative, Tanner Gibson, said Tuesday. The nature of his illness was not disclosed.
Bob Newhart remembered Mr. Poston as a "versatile and veteran performer and a kindhearted individual."
"Tom was always the 'go-to guy' on 'Newhart' in addition to being a good and longtime friend," Mr. Newhart said in a statement Tuesday.