[1] A sidearm pitcher, Littleton made his major league debut in the ninth inning of a 3–2 loss to the Toronto Blue Jays at Ameriquest Field in Arlington on July 4, 2006.

He faced two batters, retiring Vernon Wells on a groundout to the third baseman and Troy Glaus on a called third strike.

[2] Littleton failed to make the Rangers' big league roster to start the 2007 season, and was optioned to the Triple-A Oklahoma RedHawks, but was later called up to play for Texas.

Littleton was credited with a save after pitching the final three scoreless innings in a 30–3 victory over the Baltimore Orioles in the first game of a two-night doubleheader at Camden Yards on August 22, 2007.

"[3][4] On November 28, 2008, Littleton was traded to the Boston Red Sox in exchange for a player to be named later, minor league pitcher Beau Vaughan.