After completing college and some graduate work, Astin began his acting career on the New York Stage in 1954. Work included "Major Barbara" (1956) and "Tall Story" (1959), and he subsequently made his feature debut in atypically serious form as the social worker unable to really help the gangs in "West Side Story" (1961). Soon, though, he became typed in comedy, performing in the Doris Day sex farces "That Touch of Mink" (1962) and "Move Over, Darling" (1963) and later acting roles, often as Permapressed types who spin out of control, in films ranging from the deservedly obscure ("Bunny O'Hare" 1971) to the intriguing (Brian De Palma's early effort "Get to Know Your Rabbit" 1972) to the more mainstream (Disney's "Freaky Friday" 1976). He also ventured briefly into producing and directing with the Oscar-nominated short subject "Prelude" (1968).

Astin's move to comedy came about because of the wide visibility he quickly received on TV sitcoms. His first such series was "I'm Dickens ... He's Fenster" (ABC, 1962-63), in which he played the henpecked and more responsible Dickens to Marty Ingels' wilder, swinging bachelor. Astin, though, soon dropped the reserve with the popular series (partly because of its later success in syndication) and the role with which he is still most fondly associated. "The Addams Family" (ABC, 1964-66) was inspired by Charles Addams' delightful cartoons about a hilariously ghoulish family. The show, though shaped by the rules of TV sitcoms as much as Addams' vision, proved an enjoyably tonic alternative to the bland family comedies of the era, with Astin in wonderful form as paterfamilias Gomez, forever chomping his cigar, enjoying his children's misdeeds, blowing up toy trains, and lustfully kissing his wife's arm whenever she spoke French.

Astin never starred in another really successful series, but he did play a recurring role as Phyllis Diller's cousin on "The Pruitts of Southampton" (ABC, 1966-67), the leading role of the WWII submarine captain coping with "Operation Petticoat" (ABC, 1977-78), the pompous drama critic on one of Mary Tyler Moore's failed sitcoms, "Mary" (CBS, 1985-86) and one of the inhabitants of the strange but amusing town of "Eerie, Indiana" (NBC, 1991-92). Astin was less successful as The Riddler on TV's "Batman" in the mid-60s than Frank Gorshin had been, but he playing engaging recurring roles on "Simon and Simon" and "Night Court" in the 80s. He was especially good as Buddy Ryan on the latter, a mental patient who turns out to be the father of presiding judge Harry Stone (Harry Anderson). Astin also extended his creative capacities when he became a TV director in the early 70s. His output into the 80s was prolific, and he helmed many TV pilots and episodes of series ranging from "Night Gallery" (NBC, 1971-73) to "CHiPs" (NBC, 1977-83) to "Just Our Luck" (ABC, 1983-84).

Acting on and directing so much TV kept Astin off the big screen for over a decade from the mid-70s until he performed in such derivative fare as "Teen Wolf Too" (1987). Astin soon thereafter created the role of the crazed Professor Gangrene, planning to take over the world by turning tomatoes into people, in the aggressively low comedy of the horror spoof sequel "Return of the Killer Tomatoes" (1988) and subsequently "Killer Tomatoes Strike Back" and "Killer Tomatoes Eat France!" (both 1991). Other spoof work came in "Silence of the Hams" (1994) and more sequel activity with "Gremlins 2: The New Batch" (1990). A more original and prestigious undertaking, though, arose via talented director Peter Jackson's "The Frighteners" (1996), with Astin almost unrecognizable, but on still familiar turf, as an amusing if menacing ghost.