Stephen Zachary Day (born June 15, 1978) is an American former right-handed sinker-ball pitcher in Major League Baseball.

He spent four seasons in the organization before being sent to the Cleveland Indians alongside Jake Westbrook in July 2000, to complete a trade for David Justice.

He also had one save, in which he pitched the final three innings in perfect fashion (0 runs, 0 hits, 5 strikeouts) to nail down a 4–3 win against the Florida Marlins.

He hit the Disabled List in July with a shoulder injury and then again in August after breaking his middle finger trying to bunt.

However, after five appearances, Day was placed on the 60-day DL on May 23 for right shoulder tendinitis and underwent rotator cuff surgery on June 6, ending his 2006 season.

On January 11, 2008, Day signed a minor league contract with the Minnesota Twins, but was released in early May having made 6 appearances for the Fort Myers Miracle.