John Frederick "Jack" Lenz is a Canadian composer. He has written, performed, and produced music for film, television, and theatre, along with working on non-soundtrack album ventures. He is also the founder of Live Unity Enterprises, an organization devoted to the production of music for the Baháʼí community.
Lenz contributed additional music for the John Debney score for Mel Gibson's film The Passion of the Christ. Among his current projects is working on a movie about the persecution of Baháʼís in Iran, particularly the story of Mona Mahmudnizhad who suffered under the persecution in Iran, under the title of Mona's Dream. He was music director of 90 Minutes Live, with Peter Gzowski on CBC Television from 1976 to 1978.
He resides in Toronto, Ontario.