Michael Stephen Portnoy was born April 20, 1967 in Long Beach, New York. His father was a DJ so Mike was exposed to many different bands growing up, such as Queen, Led Zeppelin, and The Beatles, all of whom he would later name as having influenced him. He taught himself to play the drums and was involved with many local bands, eventually being awarded a scholarship to Berklee College of Music in Boston, Massachussettes. It was there that he met John Myung and John Petrucci and formed the band Majesty, which would later become Dream Theater.
In addition to Dream Theater, Mike is a collaborator on many additional projects. His first and arguably most successful collaborative effort was Liquid Tension Experiment with Jordan Rudess, John Petrucci, and Tony Levin. He has also worked with OSI, Neal Morse, and Transatlantic in addition to many tribute bands honoring Rush, Led Zeppelin, The Who, and The Beatles. He also served as an interim drummer for the band Avenged Sevenfold during 2010 after the tragic death of James "The Rev" Sullivan.
In September 2010, Mike announced he was leaving Dream Theater. In a personal statement he explained that:
"We have been on an endless write/record/tour cycle for almost 20 years now (of which I have overseen EVERY aspect without a break) and while a few months apart from each other here and there over the years has been much needed and helpful, I honestly hoped the band could simply agree with me to taking a bit of a 'hiatus' to recharge our batteries and 'save me from ourselves'... Sadly, in discussing this with the guys, they determined they do not share my feelings and have decided to continue without me rather than take a breather...I even offered to do some occasional work throughout 2011 against my initial wishes, but it was not to be..."
Since leaving Dream Theater, Mike has announced that he has started working on several projects, including a project with Russell Allen, Mike Orlando and Paul DiLeo titled Adrenaline Mob. Mike has also started a separate project with guitarist John Sykes and an undisclosed third band member.
Mike is an avid collector (especially of Dream Theater memorabilia), and he loves watching movies in his spare time. He currently resides in Pennsylvania with his wife Marlene, their daughter Melody, and son Max.