Ken Mandelbaum is an American columnist, critic, and author whose primary field of expertise is musical theatre.

Born and raised in Brooklyn, New York, Mandelbaum was introduced to Broadway musical theatre by his parents and grandparents at an early age. He initially pursued an acting career, studying with Stella Adler and performing at the Circle in the Square Theatre and the Provincetown Playhouse.

In 1986, he began writing for Show Music magazine^[1] and the New York Native, and the following year he joined the staff of TheaterWeek.^[2] He was a frequent contributor to Playbill and wrote a regular column for Broadway.com until 2006. Before his career as a theatre writer, he was a teacher in New York public schools.

He is the author of A Chorus Line and the Musicals of Michael Bennett (St. Martin's Press, 1989, ISBN 978-0-312-03061-2)^[3] and Not Since Carrie: Forty Years of Broadway Musical Flops (St. Martin's Press, 1992, ISBN 1466843276).^[4]

Both books are regarded to be important discussions of their respective topics by theatre historians and musical theatre buffs. Kirkus Reviews called A Chorus Line a "Must-read history of musical theater."^[3] The New York Times called Not Since Carrie a "must read", saying, "Mr. Mandelbaum hits all the highlights, everything from 'Breakfast at Tiffany's,' starring Mary Tyler Moore as Holly Golightly, to last season's 'Shogun: The Musical.' Mr. Mandelbaum also takes a good swipe at 'Annie 2: Miss Hannigan's Revenge'".^[5]