Harrison is a real strong diesel engine and the fastest engine from Chuggington, he thinks he's the cat's whiskers (the vents on his face even make him look a bit like a cat). It doesn't help that young Wilson looks up to him like a hero. Though he is vain and prideful he leans towards the vanity levels of Sir Reginald as opposed to Gordon or Farnsworth, he is a hardworker and when he gets his comuppance, he has the courage to own up.
Harrison is based on the Union Pacific Railroad M-10003.
Harrison is painted periwinkle with silver linings.