Mavis is a black Diesel.
- Season 1 - Where's BoCo? (cameo), The New Diesel Fuel, Repairing Old Slow Coach, Mavis Strikes Out, Dave the Diesel, and Hiro Goes Home
- Season 2 - The Ironworks Diesels (cameo), Trust Paxton (does not speak), and Mavis and the Track Repairs
- Season 3 - Harvey Goes Fishing and Tornado the Lost Engine
- Season 4 - A Blue Mountain Disaster! and Koby and Bumble
- Season 5 - Quinton's Vengance (does not speak), Gordon Gets Crushed (does not speak), Diesel and the Famous Visitors, and "It's A Great Story After All....."
- Season 6 - The Wrong Sort of Coal (does not speak),