Mr. Wallach was never a star of the caliber of fellow Method actors Marlon Brando (who was a fellow student at Parsons New School for Social Research in New York), Rod Steiger or Montgomery Clift, but he was regularly categorized by critics and his colleagues as among the great talents of his generation. Critic Eric Bentley, never easy to please, called him an "artist" and one of his favorite actors. Unprepossessing physically and not terribly handsome, stardom came late to him in both theatre and movies. The leading role of a simple truck driver romancing a reticent widow in Tennessee Williams' 1951 work The Rose Tattoo brought him widespread attention as a theatre performer, as well as a Theatre World Award and a Tony Award.

Five years later, it was Williams again, along with director Elia Kazan, who handed him his film debut, as a vengeful Silva Vacarro, who connives to seduce the child-bride (Carroll Baker) of cotton rival Archie Lee Meighan (Karl Malden) in the controversial 1956 drama "Baby Doll." He was in his early 40s at the time. (Mr. Wallach was to have made his film debut as Angelo Maggio in "From Here to Eternity," but, in a bit of infamous Hollywood legend, was replaced by Frank Sinatra at the last moment. Wallach later said, "Whenever Sinatra saw me, he’d say, 'Hello, you crazy actor!'")

A slew of memorable supporting turns in offbeat cinematic classics followed "Baby Doll," including a two-faced pilot in the Arthur Miller-penned "The Misfits," opposite Clift, Clark Gable and Marilyn Monroe; Calvera, the nasty Mexican bandit in the action classic "The Magnificent Seven"; and The General in "Lord Jim" with Peter O'Toole. His dark, ethnic looks won him villain roles early on. He found particular fame for his juicy performance of the thieving, greedy, unlucky desperado Tuco, the frequent patsy of Clint Eastwood's squinting, laconic stranger in the Spaghetti Western "The Good, the Bad and the Ugly." The film by Sergio Leona was a worldwide hit. (The filmmaker and actor later had a falling out when Leone reneged on an offer to use Wallach in "A Fistful of Dollars.")

Many of his characters were unsavory and untrustworthy, but they were also grittily human and rarely less than fascinating in Mr. Wallach's hands. "Eli Wallach's essential screen character," wrote Richard Schickel in the New York Times, "is a curiously lovable combination of slyness and bluster, often enough Hispanic, Asian or Italian. His function... is to pose a comically sneaky, occasionally comically brutal threat to the hero before getting a poetically justifiable comeuppance in the final reel."

His screen persona was in distinct contrast to his private self, which was agreeable, affable and garrulous. "I always end up being the evil one," he once said, "and I wouldn't hurt a fly." He remained faithful to the stage during the years of his greatest fame, returning regularly to Broadway and Off-Broadway. Following The Rose Tattoo, he was in the original productions of Williams' experimental Camino Real and John Patrick's The Teahouse of the August Moon. He helped introduce American audiences to the work of Eugene Ionesco in a double bill of The Chairs and The Lesson in 1958, and the 1961 U.S. premiere of Rhinoceros, in which he played the hapless hero opposite Zero Mostel. In 1956, he starred in a revival of Shaw's Major Barbara with Charles Laughton. Mr. Wallach's reputation as an actor had spread so wide by that time that Laughton said to him, prior to rehearsals, "I don't want any of that Stanislavski shit from you."

He starred in Murray Schisgal's huge 1964 hit Luv, and in Staircase with Milo O'Shea. In the 1970s, he acted in Promenade, All, The Waltz of the Toreadors and Saturday, Sunday, Monday. In the 1990s, he took on roles in revivals of Miller's The Price and Odets' The Flowering Peach, as well as a prominent 1998 Off-Broadway role in Visiting Mr. Green.

In many of these productions, he co-starred alongside his wife Anne Jackson. In theatre circles, the couple were as legendary for their long marriage—and equally long artistic collaboration—as had been Alfred Lunt and Lynn Fontanne, or Jessica Tandy and Hume Cronyn. They married in 1948 and had three children, including actress Roberta Wallach.

Eli Herschel Wallach was born Dec. 7, 1915, on Union Street in what was then the dangerous, waterfront neighborhood of South Brooklyn. His was the only Jewish family in a heavily Italian neighborhood. Docks boss Antonio Anastasia, brother of Murder Inc. mobster Albert Anastasia, was born across the street. He grew up above the candy story his parents, Bertha and Abraham Wallach, ran. Eli was sent by his brother Sam to the University of Texas at Austin because it had the cheapest tuition ($30), and received a Masters at City College of New York. He then studied at the famed Neighborhood Playhouse under Sanford Meisner and Martha Graham. During World War II, he served as a staff sergeant in Hawaii in a military hospital and, later, in Casablanca and France. Back in New York, Mr. Wallach took classes in acting at the Dramatic Workshop of the New School with the influential German director Erwin Piscator, and became a charter member of the Actors' Studio.

The actor made his Broadway debut in late 1945 in the flop play Skydrift. His next few, including King Henry VIII, Yellow Jack and What Every Woman Knows, were all productions of the American Repertory Theatre and featured his future wife, Jackson, in the cast. He worked with Eva Le Gallienne in Alice in Wonderland and Katharine Cornell in Antony and Cleopatra.

Mr. Wallach's career continued into old age. He took significant supporting role in "Nuts" (1987), "The Two Jakes" (1990), "The Godfather: Part III" (1990), "The Associate" (1996), "Mystic River" (2003), "The Holiday" (2006) and "Wall Street: Money Never Sleeps" (2010).

In 2010, at the age of 95, he received a Oscar for Lifetime Achievement.