Born Sept. 2, 1925, the Detroit-born New Yorker had battled cancer in recent years, friends said.
Mr. Somlyo was the first managing producer for Tony Award Productions, and, according to the American Theatre Wing, which co-presents the awards with The Broadway League, "was the architect of the current Tony Awards structure and presentation."
He began a 37-year affiliation with the Tony Awards in 1967 while continuing other television and theatre activity. He was the awards show's managing producer for 12 years. He also worked on more than 50 network programs, for which he won four Emmy Awards.
Mr. Somlyo was president of the American Theatre Wing for five years, serving through the 2003 Tony Awards.
In recent years Mr. Somlyo maintained a production and consultancy office, and was passionate about passing his expertise and experience on to young theatre people. His career in Broadway theatre began in the late 1940s as a production assistant on Goodbye, My Fancy (1949); Caesar and Cleopatra (1950), directed by and starring Cedric Hardwicke; and The Devil's Disciple (1954). He graduated to assistant company manager of the musical Fanny and Thornton Wilder's The Matchmaker, and was a replacement company manager on the original Gypsy.
By 1961 his career as a general manager began. Some of his credits as a Broadway G.M. included famous engagements of Beyond the Fringe, An Evening With Mike Nichols and Elaine May, An Evening With Yves Montand, Hamlet starring Richard Burton, Dear World and more.
He became an associate producer or producer in later years on such shows as the musical I Remember Mama, 84 Charing Cross Road, A Day in Hollywood/A Night in the Ukraine and more.
His last Broadway credit as a producer, according to Internet Broadway Database, was for the dance specialty show, Gypsy Passion, in 1992-93.
In 2003 Mr. Somlyo, who had served as Wing president for five years, resigned but was part of the search committee to replace him.
When Mr. Somlyo joined the Wing in 1998, leaving his position as managing producer of the Tony Awards, one of his first chores was to modernize the offices, which he made fully computerized. "I am particularly proud of having just created a very special website for the Wing," Mr. Somlyo said at the time. Under his guidance Wing membership increased by 800 percent, and he left the Wing more financially secure. He also created The American Theatre Wing's Guide to Careers in the Theatre, and he turned the Wing's Spring Honors event into a lavish affair.
At the time of his exit, Mr. Somlyo was credited with maintaining the Wing's presence in connection with the annual Tony Awards ceremony; the Tonys were created as a program of the Wing, a not-for-profit service organization to the American theatre. In later years, The Broadway League (formerly The League of American Theatres and Producers) became a co-presenter.
After his work at the Wing, Mr. Somlyo became executive consultant to the Drama Desk Awards, advising that group on how its profile might be enhanced.
Mr. Somlyo was born in Detroit in 1925, one of five children of Ben and Irma Somlyo (his father was a realtor). In 1948 after a stint as a lieutenant in the Army, he earned a B.A. in economics from Wayne State University in Detroit.
During his time at WSU, according to a 2006 profile in The New York Sun, he joined a student theatre group called the Actors Company. His natural business acumen and his classwork pushed him to become the leader of the collective's business issues. He moved to New York City after graduation.
His early career, in the 1950s, also included the job of business manager at the Cape Playhouse in Massachusetts, the Cape Cod Melody Tent, Margo Jones Theatre in Dallas and a tour of the one-woman show Hildegarde.
Mr. Somlyo told the Sun that his work with director Peter Brook was "my most privileged and proudest" association. A long-running association was with Alexander Cohen; they worked on many projects, including the Tonys, over 20 years.
He married Nancy Rifici in 1957. She survives him, as do their children, David (and Anne) Somlyo and Lauren (and Michael) McGowan, and four grandchildren.
In lieu of flowers, the family requests donations to the New York Public Library for the Performing Arts at Lincoln Center.