Shawn went on to become a movie fixture of sorts, acting in as many as five films a year by the mid-1980s. He tended to appear in brief but memorable bits such as playing the radio superhero Masked Avenger in Allen's 1987 "Radio Days" ("Beware, evildoers! Wherever you are!"). He shone in a larger role that same year--the preposterous evil mastermind in Rob Reiner's engaging fairy tale, "The Princess Bride". Shawn has also worked in TV from time to time, doing several guest shots on "Taxi" and playing recurring characters on "The Cosby Show" and "Murphy Brown". He made the transition to series regular during the 1996-97 season, recreating his 1994 feature film role as a teacher in ABC's sitcom version of "Clueless". Shawn became a favorite of "Star Trek" fans with his oft-hilarious guest stints as the Ferengi Grand Nagus Zek, the financial kingping of the avaricious aliens and a frequent thorn in the side of Quark (Armin Shimmerman) throughout the series run of "Star Trek: Deep Space Nine" (syndication, 1993-1999). He would also enjoy recurring stints on "Cosby" in 1999 and as Dr. Howard Stiles on the NBC crime drama "Crossing Jordan" beginning in 2002.
Shawn's reasonably lucrative acting career helped subsidize his playwriting. A child of some privilege--his father, William Shawn, enjoyed a long reign as the editor and publisher of "The New Yorker"--he used his plays to critique the self-serving attitudes of his class and the imperial actions of his country. Shawn's first produced play, "Our Late Night", won him the 1975 OBIE Award for Best New Play. He earned that honor again in 1986 for "Aunt Dan and Lemon", about a domineering woman and her protege, and in 1991 for "The Fever", an unpleasant work about an American of unspecified age and sex who languishes violently ill on the floor of a hotel room in a foreign country while a revolution rages outside. In 1996, his play "The Designated Mourner" premiered in London, starring Mike Nichols and Miranda Richardson and directed by David Hare. That production was later filmed and released theatrically.
Shawn's recent film credits ran the gamut from silly sci-fi kidpics ("Mom and Dad Save the World" 1992) to character comedy ("The Cemetery Club" 1993) to ambitious period pieces ("Mrs. Parker and the Vicious Circle" 1994). He reteamed with Andre Gregory as he played David Mamet's take on Chekhov's Uncle Vanya in Louis Malle's "Vanya on 42nd Street" (1994), a filmed version of a run-through of the play inside a dilapidated Manhattan theater. Shawn's always welcome presence enlivened a series of middling comedies, including "Vegas Vacation" (1997), "My Favorite Martian" (1999), "Duplex" (2003) and "The Haunted Mansion" (2003), and he continued to appear regularly on television in projects ranging from serious-minded miniseries like the Marilyn Monrow bio "Blonde" (2001) to comedic fare such as the Kelsey Grammer holiday telepic "Mr. St. Nick" (2002). The actor also maintained his fruitful association with Woody Allen, appearing in the writer-director's lesser effort "The Curse of the Jade Scorpion" (2001), and he served as the man who makes the argument for the comedic storyline of Allen's dual-structured "Melinda and Melinda" (2005).
The actor's distincively lisping voice was a natural for animated projects, the most significant of which was his turn as Rex the green dinosaur in the Disney/Pixar smash hit CGI film "Toy Story" (1995) and its sequel "Toy Story 2" (1999). He also provided vocals for "A Goofy Movie" (1995), "The Lionhearts" (1998), "King of the Hill," "The Incredibles" (2004)--where he memorably voiced Mr. Incredible's demanding insuance firm boss--and as Principal Crosby Strickler on the Disney series "Teacher's Pet" (2000-20002) and its 2004 feature film spin-off.