American poet, librettist, and translator, best known for his collaborations with W. H. Auden and Igor Stravinsky.

Kallman was born in Brooklyn of Jewish ancestry. He received his B.A. at Brooklyn College and his M.A. at the University of Michigan. He published three collections of poems, Storm at Castelfranco (1956), Absent and Present (1963), and The Sense of Occasion (1971). He lived most of his adult life in New York, spending his summers in Italy from 1948 through 1957 and in Austria from 1958 through 1974.

Together with his lifelong friend (and eventual lover) W. H. Auden, Kallman wrote the libretto for Stravinsky's The Rake's Progress (1951). They also collaborated on two librettos for Henze, Elegy for Young Lovers (1961) and The Bassarids (1966), and on the libretto of Love's Labour's Lost (based on Shakespeare's play) for Nicolas Nabokov (1973). They also wrote a libretto "Delia, or, A Masque of Night" (1953), intended for Stravinsky, but never set to music. They were commissioned to write the lyrics for Man of La Mancha, but Kallman did no work on the project, and the producers decided against using Auden's contributions.

Kallman was the sole author of the libretto of The Tuscan Players for Carlos Chávez (1953, first performed in 1957 as Panfilo and Lauretta).

He and Auden collaborated on a number of libretto translations, notably Die Zauberflöte (1956) and Don Giovanni (1961). Kallman also translated Verdi's Falstaff (1954), Monteverdi's L'Incoronazione di Poppea (1954) and many other operas.

In 1963 he moved his winter home from New York to Athens, Greece and died there at the age of 54.