Harold is a helicopter who is based at the Sodor Search and Rescue Centre.
Sikorsky S-55 helicopter
When Harold was first seen, he claimed that "railways are slow and out of date", but was proven wrong by Percy after Percy beat Harold in a race. When Thomas's brakes failed and became a runaway, he helped an inspector catch up to him, and stop. He also brought Santa Claus to the Christmas Party in 1986. He has also made good friends with Duck after he rescued an injured sailor.
Harold was based at the airfield at Dryaw until the construction of the Sodor Search and Rescue Centre. Since then he has joined the team and has gone on several missions such as searching for Thomas, rescuing Bertie from the Shake Shake Bridge, rescuing sheep, and climbers, and finding a lost elephant.
Harold speaks in a manner reminiscent of an RAF pilot, using terms such as "wizard" and "old chap" in conversation. Harold somewhat tends to be full of himself as he feels that "railways are slow", but he always gets his comeuppance in the end.
Harold is painted white with red lining.
Adventures on Rails
- Season 18 - Toby and the Flood, Thomas and the Hurricane (mentioned), Percy's Big Mistake, Thomas, Percy and the Mail Train
The New Adventures on Rails
- Season 1 - Races and Where's BoCo?
- Season 2 - The Early Whirlybird, Forest Fire, and Diesel Day
- Season 3 - Mavis and the Track Repairs (cameo)
- Season 4 - Planes and Helicopters, Harold and the Climbers, Saved by the Belle, and James and Flynn (cameo)
- Season 5 - Sodor Snowstorm, Henry Saves the Day, Butch's Snow Rescue and Smoke Signals
- Thomas and Percy
The Many Adventures of the Island of Sodor
- Season 1 - A Friend in Ferdinand
- Season 2 - BoCo's Return (does not speak), Harold in Space, Max and Monty's Wasteful Day (cameo), and All for Thomas (cameo)