Timothy William "TW" Walsh (born January 26, 1975 in Melrose, Massachusetts) is a songwriter, multi-instrumentalist, record producer, mixing engineer and mastering engineer.

In August 2003, Walsh joined Pedro the Lion, led by David Bazan. The two would also collaborate on Bazan's Headphones project. Walsh was, aside from Bazan, the only other official member of Pedro the Lion, and was heavily involved in the recording of Pedro the Lion's Achilles Heel. Citing personal and financial reasons, Walsh left both projects in late 2005, after which Bazan retired the Pedro the Lion moniker. In 2009 Walsh mixed and mastered Bazan's Curse Your Branches album.