Bill Callahan was a writer and co-executive producer for Psych. He has also written and produced for shows such as Scrubs, 8 Simple Rules, and Spin City, the last being where he got his start, as a story editor.
The episodes Callahan wrote are:
- The Devil's in the Details... and the Upstairs Bedroom (August 7, 2009)
- Shawn Gets the Yips (September 11, 2009)
- Death Is in the Air (February 17, 2010)
- Not Even Close... Encounters (July 28, 2010)
- Shawn 2.0 (September 1, 2010)
- Dual Spires (December 1, 2010)
- We'd Like to Thank the Academy (December 8, 2010)
- Dead Man's Curve Ball (November 9, 2011)
- Santabarbaratown (April 11, 2012)
- Deez Nups (April 24, 2013)