Michael August Timlin (born March 10, 1966 in Midland, Texas) is a relief pitcher in Major League Baseball for the Boston Red Sox. He signed a one-year contract with the club on Saturday, December 1, 2007.

An important man in the Boston bullpen and a veteran setup man, Timlin has a good command of his 93-MPH fastball. He also throws a slider and a sinker that have a downward break, inducing a significant number of ground balls. In , Timlin made 76 pitching appearances, the third most in Red Sox history and tied for fourth in American League history. On September 3, he made his 800th major league appearance, becoming only the 29th pitcher in major league history to reach that mark. Timlin made his 1,000th career appearance on August 31, 2007, against the Baltimore Orioles.

After his first three successful seasons with the Red Sox, Timlin struggled in 2006 and the beginning of 2007 due to injuries to his right shoulder and left oblique, making multiple visits to the disabled list. In the period after his return from the disabled list through July 23, 2007, Timlin recorded over 14 consecutive scoreless innings and appeared to have overcome any shoulder issues. In the week following, however, he has again experienced shoulder soreness. Since then, however, Timlin has once again stepped in as an important setup man for the Red Sox.