John A. Costelloe (November 8, 1961 – December 16, 2008) was an American actor best known for his role as Jim "Johnny Cakes" Witowski, the fireman lover of Vito Spatafore, in the HBO TV series The Sopranos.

Costelloe, a former NYFD firefighter, died of a self-inflicted gunshot wound on December 16, 2008, at the age of 47. His body was found two days later at his home in Sunset Park,Brooklyn. Friends and family were surprised by his death, and at a loss for answers about its cause.

Shortly before his death, Costelloe had been playing a hustler in the hit ensemble play Gang of Seven.

Selected filmography

• Last Exit to Brooklyn (1989) - Tommy
• Black Rain (1989) - The Kid
• Die Hard 2 (1990) - Sergeant Oswald Cochrane
• The Hard Way (1991) - Fake Dead Guy / Cop
• Billy Bathgate (1991) - Lulu
• Joey Breaker (1993) - Randy Jeter
• Manhattan Murder Mystery (1993) - Policeman
• Who Do I Gotta Kill? (1994) - Billy "Bink-Bink" Borelli
• New York Undercover (1994–1996) - John Santucci
• Kiss of Death (1995) - Cleary
• Kazaam (1996) - Travis
• Law & Order (2000) - Colin Parnell
• Crooked Lines (2003) - Manny
• The Kings of Brooklyn (2004) - Miller
• The Sopranos (2006) - Jim Witowski
• Doubt (2008) - Warren Hurley (Last appearance)