Katy Perry
Written by Katy Perry
Glen Ballard
Produced by Glen Ballard

"Sherlock Holmes" is a song written by Katy Perry and Glen Ballard. It was recorded for Perry's unreleased album, (A) Katy Perry. Perry was asked on the Katy Perry Forum if she would ever re-record her unreleased songs and she mentioned "Sherlock Holmes" in the answer.

My favorite outta all the ones you mentioned [It's Okay to Believe, Diamonds, Simple...] though was "Sherlock Holmes" I always think that song needed a lyric change and a rerecord on all fronts and it would be great!

—Katy Perry