Although Cronyn garnered a Supporting Actor Oscar nomination as the dull-witted friend who helps Spencer Tracy avoid the Gestapo in "The Seventh Cross" (1944, his first film with wife Jessica Tandy), roles like his Nazi collaborator in "The Cross of Lorraine" (1943) and the despicably ruthless prison guard captain in "Brute Force" (1947) marked him as a baddie. In an effort to escape such typecasting, he turned down the plum part of the sadistic killer played by Richard Widmark in "Kiss of Death" (also 1947) and successfully broke out of the villain mold to enjoy a varied film acting career, playing everything from a jealous physician in "People Will Talk" (1951) and Roosevelt's gruff counselor Louis Howe in "Sunrise at Campobello" (1960) to half of a bickering old homosexual couple in "There Was a Crooked Man" (1970) and Warren Beatty's editor in "The Parallax View" (1974). Cronyn's Tony-winning stage performance as Polonius opposite Richard Burton's "Hamlet" (1964) made it to the screen via a filmed record of the Broadway production directed by John Gielgud.

Cronyn's directing debut at the helm of Tennessee Williams' one-act play "Portrait of a Madonna" starred wife Tandy and led directly to her landing the role of Blanche in Williams' "A Streetcar Named Desire" on Broadway. The two first acted together on stage in Broadway's "The Fourposter" (1951), a play they would eventually perform more than 600 times over the years. Subsequent plays like Edward Albee's "A Delicate Balance" in the 60s, "The Gin Game" in the 70s and "The Petition" in the 80s established them as the successors to Alfred Lunt and Lynn Fontanne as the pre-eminent married acting couple of the American theater, culminating in a shared Special Lifetime Achievement Tony in 1993.

"Honky Tonk Freeway" (1981) reunited them for the first time in features since 1946, and over the next 13 years, Tandy and Cronyn would act together in five more films, as Glenn Close's parents in "The World According to Garp" (1982), as a married couple in "Cocoon" (1985), its 1988 sequel and "*batteries not included" (1987) and their final onscreen appearance as former lovers in "Camilla" (1994), released after Tandy's death. In addition to televised version of their stage work, Cronyn and Tandy co-starred in the short-lived series "The Marriage" (NBC, 1954) and their final small screen collaboration was in the poignant CBS "Hallmark Hall of Fame" presentation "To Dance With the White Dog" (1993), for which he won one of this three Emmy Awards.

Cronyn began his association with Susan Cooper, co-writing "Foxfire", the 1980 Broadway play co-starring Tandy and him. Cronyn and Cooper continued their collaboration on "The Dollmaker" (ABC, 1984), starring Jane Fonda in her TV-movie debut, which earned the pair Writers Guild and Christopher Awards for their teleplay. It was at Cooper's urging that he wrote "A Terrible Liar", his 1991 autobiography chronicling the Cronyns' life together through 1966, and they expanded on their partnership (which also yielded the as yet produced screen adaptation of Anne Tyler's novel "Dinner at the Homesick Restaurant") by marrying in July of 1996.

After taking some time off following Tandy's death, Cronyn resumed working, portraying the dying patriarch to Diane Keaton and Meryl Streep in "Marvin's Room" (1996), then acting on TV in the Showtime movies "12 Angry Men" and "Horton Foote's Alone" (both 1997) and the CBS miniseries "Seasons of Love" (1998). Home movies shot by Cronyn and Tandy on their journey to East Africa in 1966, augmented by footage from his return there in 1995, became "An African Love Story" (Disney Channel, 1996).

Cronin close out a long and enviable career before the cameras with appearences in several made-for-TV movies, including the heartwarming Christmas tale "Santa and Pete" (1999), in which he played St. Nicholas, and "Off Season" (2001), directed by his on-stage "Glass Menagerie" co-star Bruce Davison. Cronin passed away in 2003 at the age of 91.