Michael Stephen Portnoy is an American musician who is primarily known as the drummer, backing vocalist, and co-founder of the progressive metal band Dream Theater.

Transatlantic is a multinational progressive rock supergroup consisting of Neal Morse, Roine Stolt, Pete Trewavas and Mike Portnoy. They formed in 1999 as a side project to their full-time bands, but disbanded in 2002. They then reunited in 2009.