Pendleton worked steadily onstage, mostly in New York and New Haven, though he spent the 1966-67 seasons with San Francisco's American Conservatory Theater. On the East Coast, Pendleton appeared in "Fiddler on the Roof" (1964) as Motel, the tailor, played Leo in "The Little Foxes" (1967), appeared in the title role of "The Last Sweet Days of Isaac" (1970-72) and twice played "Tartuffe" (in 1974 and 1977). He also excelled as a director, helming more than a dozen stage projects in New York, New Haven and Williamstown. In 1981, he directed Elizabeth Taylor's Broadway debut as Regina in "The Little Foxes".
Pendleton has dabbled in TV from time to time, beginning with the variety special "Let's Celebrate" (ABC, 1972). He appeared with Stephen Sondheim in "June Moon" (PBS, 1974) and played Ethel Merman's son in the CBS pilot "You're Gonna Love It Here" (CBS, 1977). Another failed pilot entailed a rare starring role, as a free-spirited PR man in "Big City Boys" (CBS, 1978). A handful of projects followed, including "Love, Long Distance" (CBS, 1985) and Woody Allen's "Don't Drink the Water" (ABC, 1994).
But films have brought Pendleton great acclaim as a busy supporting player. His debut was in Otto Preminger's gangster comedy "Skidoo" (1968) and Pendleton spent the next few years in comedy. He co-starred in Mike Nichols' "Catch-22" (1970), was Ryan O'Neal's prissy boss in Peter Bogdanovich's "What's Up, Doc?" (1972), reteamed with O'Neal in "The Thief Who Came to Dinner" (1973), was an endearing henchman in "The Muppet Movie" (1979) and played Shirley MacLaine's duplicitous chauffeur in "Guarding Tess" (1994). Most of his other films were also-rans, like "First Family" (1980), "Off Beat" (1986), "Hello, Again" (1987) and "Greedy" (1994), but Pendleton's supporting-player status assured that he didn't bear the brunt of critical disdain.
There have been, of course, other opportunities for Pendleton to shine. He had small but memorable roles in James Ivory's "Mr. and Mrs. Bridge" (1990) and as a bumbling public defender in "My Cousin Vinny" (1992). The still-busy actor appeared as Holly Hunter's boss in Jodie Foster's second directorial outing, "Home for the Holidays" (1995), played a philandering psychiatrist in "Two Much" (1996) and was featured in Barbra Streisand's "The Mirror Has Two Faces" (1996).