Romantic English poet Percy Bysshe Shelley was born on July 8, 1792. To the contemporary ear, the image of the name Percy is more geek chic and less rebel poet like its famous bearer. Usage of the name in the US has doubled in the past decade, though Percy still ranks below the Top 1000. A handful of baby girls are named Percy in the US each year too.
Percy is very "old man" style to me. However, the only 2 associations I have with this name are #1-from Thomas the Train (a friend of Thomas) and #2- from Little House on the Prairie (Nellie was married to a Percival). A name close to Percy that appeals to me more is Perry which I feel could be used for boy or girl.
My Percy turned 2 on Sunday! Such an underrated name!