Mavis is a quarry shunter from The Island of Sodor.
Mavis was arrogant and did not take advice very well. She was mostly interested in her own ideas, but was brought down to earth after her embarrassing incident at a crossing. With a little help from Toby, she now finds better ways to be really useful and knows more about handling and arranging trucks. Mavis is a reliable, honest, and hard-working engine.
Unusually for a diesel, Mavis shows respect for the steam engines, and unlike most engines, hauling trucks makes her feel important.
Mavis has now fully matured, and acts as a motherly figure to the other engines.
Mavis is a based on the BR Class 04 0-6-0 diesel locomotive. She is more specifically based on the BR Class 04's that worked on the Wisbech and Upwell Tramway, as they were fitted with additional cowcatchers and sideplates so they could run near public roads. 18 of these locomotives are preserved, including one "tramway" example.
Mavis is painted black with yellow hazard stripes on her front and rear. She has her name and "The Ffarquhar Quarry Co. Ltd." written in white on her cab and sideplates respectively.