Whiff is a grubby green tank engine who collects rubbish. His main task is collecting rubbish and scrap, which explains his dirty appearance and smell.
When Whiff first came to the railway, Emily was asked to help him out. Emily was under the impression that he would be more intriguing and that the task would be more exciting; Emily was eager at first, but disappointed when she learned that Whiff worked with rubbish. Emily tried to avoid being seen with him, but Whiff found her almost everywhere she went. Although the two were mocked by other engines wherever they went, Whiff maintained a cheery expression and seemed either not to notice or care. When Emily finally escaped from Whiff, she found Spencer blocked by a long line of trucks full of rubbish. When none of the other engines helped, she found Whiff. Emily apologised to Whiff, and together they cleared Spencer's line.
Whiff was present at the celebration of Sodor Day at the newly reopened Great Waterton station.
One day, Whiff was meant to take away a truck of old cans from a siding. Toby, who was looking for something special to present to the Fat Controller, mistook the distant truck at first for something valuable. Later, Whiff brought the Fat Controller to a broken-down Toby, who had discovered a sign belonging to the old Sodor Tramway.
He later gained his own rubbish dump and with help from Percy, he unblocked the tunnel to Misty Island and saved Thomas, Bash, Dash, and Ferdinand.
Whiff now runs his dump with help from Scruff. One day, when Scruff's "scruncher" was broken, Whiff stayed with him at the Sodor Steamworks until he was mended. This left the rubbish dump without anyone to run it, so Gordon was put in charge for the day.
Whiff requires help from time to time with his rubbish trains. Once, Thomas was supposed to help Whiff with his train, but only succeeded in crashing into the trucks at Wellsworth as Thomas was trying to stay clean for the Duchess of Boxford. In the end, Whiff took the Duchess whilst Thomas cleared up the mess and took the rubbish train. Later on, Whiff tried to be as grand as Spencer by hauling heavy loads. He helped Emily and Edward by taking some of their loads, but only neglected his own job of clearing the railway of the rubbish trucks. After delivering the respective loads, Whiff carried out his work and proved once again to be really useful.
Whiff and Scruff helped Thomas on getting covered in rubbish so he can play a trick on Diesel, and later attended the Earl of Sodor's Christmas lunch.
Whiff is cheerful and optimistic. He enjoys his job of collecting rubbish. He doesn't seem to care what the other engines think about him: either that or he is oblivious to their opinions. Despite that, he is friendly and always does his job well. He is somewhat naive, as he didn't realise why the other engines tried to avoid him so much. However, in Misty Island Rescue, he is shown to know about Sodor's history, since he knew about the tunnel connecting Misty Island to Sodor.
According to Whiff's TV series designer, Whiff can also be described as "nerdy".
Whiff is based on the North Eastern Railway's 2-2-4T No. 66, known as Aerolite; the engine was classed as X1 by the LNER in 1923 and retired in 1934. It can be found today at the National Railway Museum in York.
Whiff is painted in a dark green livery with black and gold stripes and green wheels. He wears large spectacles on his smokebox.
- Keith Wickham (UK; Misty Island Rescue - Twentieth Season)
- Lee Ingleby (Twenty First season onwards)
- William Hope (US; Misty Island Rescue onwards)
- Whiff is the first and only engine to wear glasses in the television series. However, if Railway Series characters were counted, Whiff would be the second character, the first being the Ballast Spreader.
- Throughout Nitrogen Studios' tenure, Whiff's whistle budges up and down when he blows it.
- Whiff has the same number as his basis, Aerolite.
- Whiff has been shown to pull more trucks than his basis is capable of pulling.
- Whiff has gone through a few changes in the television series:
- Season 12
- His glasses gained lenses.
- Misty Island Rescue:
- His whistle budges up and down.
- Season 17:
- His whistle becomes stationary again.
- Season 18
- Whiff gained a permanent headlamp and lamp iron.
- Season 12
- Wooden Railway (discontinued; reintroduced 2014)
- Take Along (discontinued)
- My First Thomas (talking)
- Wind-up Trains (Japan only)
- Boss (discontinued)
- My Thomas Story Library (discontinued)
- Collectible Railway
- Micro Rubber Engines
- Mega Bloks (discontinued)