Jim Jacobs, born on October 7, 1942, in Chicago, Illinois, is an American actor, composer, lyricist, and writer for the theatre, prominently known for his work on the musical "Grease." Raised by his parents Harold, a factory foreman, and Norma (Mathison) Jacobs, Jim attended Taft High School where he played guitar and sang with a band called DDT & the Dynamiters. Influenced by rock and roll icons like Bill Haley, Elvis Presley, Buddy Holly, Little Richard, and Jerry Lee Lewis, Jacobs developed a passion for music early on, teaching himself guitar after a brief stint with formal lessons.

In 1963, Jacobs joined the Chicago Playwrights Center, where he met Warren Casey. This collaboration led to the creation of "Grease," a musical inspired by Jacobs's high school experiences and the early rock and roll era. The original production premiered in 1971 in Chicago before becoming a Broadway hit and later a successful film adaptation in 1978. Jacobs's work on "Grease" has left a lasting impact on musical theatre, celebrated for its nostalgic portrayal of 1950s youth culture.

Beyond "Grease," Jacobs has been involved in over fifty theatrical productions in Chicago and worked as an advertising copywriter. His personal life includes partnerships with Diane Rita Gomez, Denise Nettleton, and Karyn Kobayashi, and he is a father to four children.