Whiff is a grubby tank engine who collects refuse. His main task is collecting rubbish and scrap, which explains his dirty appearance and smell.
Whiff was a 2-2-2WT built in 1869 with side tanks were added in 1886. The number 66 and spectacles were added at about this time. In 1892, Whiff was rebuilt into a 4-2-2. The well tank was removed, the side tanks expanded, and the two-cylinder Worsdell-von Borries compounding system applied. In 1902, he was again rebuilt into a 2-2-4T. Whiff was fitted with Westinghouse brakes. A vacuum ejector was fitted in 1928 as a part of an LNER initiative to standardise braking systems. Raven fog signalling apparatus was also fitted.
When Whiff first came to the railway in 2007, 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 garbage. 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 Whiff, she found Spencer blocked by a long line of trucks full of garbage. When none of the other engines helped, she found Whiff. Emily apologised to an understanding Whiff, and together they cleared Spencer's line.
One day in 2008, 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.
Whiff is cheerful and optimistic. He enjoys his job of collecting garbage. 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.
Whiff is based on the North Eastern Railway's 2-2-4T "66", known as Aerolite; the engine was classed as X1 by the LNER in 1923 and retired in 1934, approx. 32 ft 8 1/2 long. It can be found today at the National Railway Museum in York. Whiff also carries his basis' number.
Whiff is painted in a dark green livery with black and gold stripes and green wheels. He wears large spectacles on his smokebox.
- Whiff has a high-pitched two-chimed whistle.