Biography: Dean Winters (born July 20, 1964) is an American actor, who is known for his roles as Bobby on the YouTube series Wayne, Detective Brian Cassidy on Law & Order: SVU, Detective Russ Agnew on Battle Creek, 'The Vulture' Detective Pembroke on Brooklyn Nine-Nine, Charley Dixon on FOX's Terminator: The Sarah Connor Chronicles, Dennis Duffy on NBC's 30 Rock, Johnny Gavin on FX's Rescue Me, Ryan O'Reily on HBO's Oz. He also portrays "Mayhem" in Allstate commercials.