Percy is a green saddle tank engine from The Island of Sodor. He works on the Inkblotia-Celgreb City Branchline with Thomas, Toby and Tootle and pulls the mail train on Crotoonia with Johnny, Tracy, The Greendale Rocket & Tillie.
Percy is a rather cheeky, but kind engine, and generally behaves well, except when he is getting into mishaps from being over-eager. He loves teasing the others, especially the bigger engines, such as Gordon and James, but is always brought down to earth in due course by anyone who gives him the moral to learn.
Percy has some trouble learning difficult words: he would say "dingy-fried" where anyone else would say "dignified," "demonstration" into "dimer-station," "railway inspector" into "railway inspectacles," "new-fangled nonsense" into "new-funneled nuisance", "action" into "act-on", or "V.I.P." into "V eyed-p." He is also shown to make mistakes, but then fix them upon realising what he has done before further damage is caused.
Percy is incredibly accident-prone and has many accidents, sometimes due to his own silliness or his tricks backfiring. Despite this, he always tries to do his best, learn from his mistakes and get his jobs done, a loyalty which he has been praised for on several occasions.
Although their friendship has been turbulent at times, Thomas is generally portrayed as Percy's best friend, he is also good friends with Toby as well. Percy has had a small rivalry with Harold, stemming from their race. However, they are always willing to help each other when in trouble.
Percy is an 0-4-0 saddle tank believed to have been built originally by the Avonside Engine Company of Bristol but prior to being purchased second or third hand by Sir Topham Hatt he acquired components from Hunslet of Leeds and other builders.
Percy is painted in the North Western Railway's green livery with red and yellow lining and the number "6" painted on his bunker sides in yellow.
- There were two Percy models used in Crotoonia. The first one was used in the first two Crotoonia music videos.