Orbach was born the son of a father who was a restaurant manager, but had once worked in vaudeville and a mother who was a radio singer in the New York City borough the Bronx. His family moved around during his childhood, settling in Waukegan, IL, when he was 11. Having skipped grades, he graduated from high school at 16 and attended the University of Illinois for a year before transferring to Northwestern University, where he stayed for two-and-a-half years before leaving to launch his career. Moving to New York City, he studied with such famed acting teachers as Herbert Berghof and Lee Strasberg. In 1955, he was hired as an understudy in the long-running Off-Broadway revival of The Threepenny Opera. Over the next three years, he gradually worked his way up in the cast to the point that, in 1958, he began playing the lead role of Macheath (aka Mack the Knife). The same year, he made his film debut with a small part in Cop Hater. He moved to another long-running Off-Broadway success originating the role of the narrator El Gallo in The Fantasticks (May 3, 1960), a part that allowed him to introduce the standard "Try to Remember." He made his recording debut on the original cast album, which reached the charts. He then made his Broadway debut in Carnival (April 13, 1961). The musical was a hit, running 719 performances, and the cast album reached number one. Both of the cast albums on which Orbach had appeared were released by MGM Records, which signed him as a recording artist and in 1963 released his only solo album, Off Broadway. (The album was reissued on CD on Decca Records in July 2000.)
Orbach appeared in a series of revivals of notable musicals in the mid-'60s: an Off-Broadway production of The Cradle Will Rock (1964) and limited-run Broadway stagings of Guys and Dolls (April 26, 1965), Carousel (August 10, 1965), and Annie Get Your Gun (May 31, 1966). His performance in Guys and Dolls earned him his first Tony Award nomination as a supporting actor in a musical, but that show was the only one of the four not to produce a cast album. In 1967, he made his debut on Broadway as a non-singing actor in the comic play Scuba Duba. He originated his second starring role in a Broadway musical in Promises, Promises (December 1, 1968), singing the title song and the standard "Ill Never Fall in Love Again." The show ran 1,281 performances and produced a charting cast album; Orbach won the Tony Award for leading actor in a musical.
Orbach had had roles in a couple of more films (Mad Dog Coll , John Goldfarb, Please Come Home ), but it was not until 1971 that he got a starring role on film in the crime comedy The Gang That Couldn't Shoot Straight. His film career was not yet ready to take off, however, and he returned to the Broadway stage in the comic play 6 Rms, Riv Vu in 1972. He was given his third opportunity to originate a starring role in a Broadway musical with Chicago (June 1, 1975). The show ran 923 performances and produced a charting cast album, while Orbach earned his third Tony Award nomination for lead actor in a musical. He made his last appearance in a Broadway musical with 42nd Street (August 25, 1980), which ran 3,486 performances and had a cast album that reached the charts.
Orbach had continued to take the occasional film role (A Fans Notes , Foreplay , The Sentinel , Underground Aces ), but it was his appearance in Prince of the City (1981) that was a turning point in his career. Now in his mid-forties, he had matured into a gruff, sleepy-eyed tough guy type, perfect for playing cop characters, which he did here. (The persona did not prevent him from appearing in comedies as well, however.) After leaving 42nd Street, he began to appear frequently in films: Brewsters Millions (1985), The Imagemaker (1986), F/X (1986), Dirty Dancing (1987), I Love N.Y. (1987), Someone to Watch Over Me (1987), Crimes and Misdemeanors (1989), Last Exit to Brooklyn (1989), Delusion (1990), California Casanova (1991), Dead Women in Lingerie (1991), Toy Soldiers (1991), Out for Justice (1991), Delirious (1991), The Cemetery Club (1992), Straight Talk (1992), Universal Soldier (1992), and Mr. Saturday Night (1992). He also briefly returned to his roots in musical comedy by serving as one of the voices in the animated Disney movie musical Beauty and the Beast (1991), also appearing on the soundtrack album, as Lumiere, the French-accented candelabra who sings "Be Our Guest." (He continued his work with Disney in the straight-to-video animated films Aladdin and the King of Thieves  and Belles Magical World , the latter a sequel to Beauty and the Beast.)
Orbach also worked regularly in television, making many TV movies and also guest-starring on several series. In the 1987-1988 season he starred in his own show, The Law and Harry McGraw, a spin-off of Murder, She Wrote, playing a private detective. He was nominated for an Emmy Award for Outstanding Guest Actor in a Comedy Series for his appearance on The Golden Girls during the 1989-1990 season. In 1992 he replaced Paul Sorvino in the long-running dramatic series Law and Order, playing Detective Lenny Briscoe; he remained with the show for an extended period and eventually becoming best known for his part on the show. He also continued to make the occasional film appearance: A Gnome Named Gnorm (1994), To Wong Foo, Thanks for Everything! Julie Newmar (1995), Prince of Central Park (1999), Chinese Coffee (2000), and The Acting Class (2000).
After 12 seasons on Law & Order, Orbach agreed to move to the spin-off series Trial by Jury in early 2004. Around the same time, he was diagnosed with prostate cancer. He shot several episodes of the new series before succumbing at the age of 69 on December 28, 2004, in New York. ~ William Ruhlmann, Rovi