Cormac is an Very Evil Character of Thomas and Friends. He is the Diesel Empire's courier (Introduced in Clay TV Series S1. Ep17). He was killed in Battle for the Rails when he fell off the Bridge of the Gods, But Revived in the Another Clay TV Series Seasons (S2, 3, 4, 5, 6), He is the Main Antagonist of the Magical Island Diaries. He can combine with his brother Dennis to create Gran Belphegor.
- Class: EMD GP38- 2 Bo-Bo
- Number: D1678
- Friends: Daisy, Diesel & Diesel 10
- Other Friends: Spencer, Norman, Sidney, Splatter & Dodge, Arry, Bert, & Quorton.
- Rivals: Gator, Paxton, Zeakerp Tao, Loly, Fabian, Manuel, Daniel, Emerald Night
- Enemies: Thomas, Edward, Henry, Gordon, James, Percy, Toby, Duck, The Scottish Twin, Oliver, Emilie, Bill & Ben, Bagny, Charleen, Sir Topham Hatt Hiro, Ajax, etc.
- Family (formerly): Dennis (brother), Bulgy (pet), Elizabeth (girlfriend)
Cormac's Theme is the Boss Fight Theme from "Conker's Bad Fur Day"
Counterparts (Thomas Version)
- Toad the Robot (Super Smash Bros. Brawl)
- Dick Dastardly (World of Doki)
- The Dastardly Emperor (Vehicles)
- Mad Infection Turagha (Bionicle)
- Dr. Meowthidious (Pokemon)
- Kragok or Lord Utsire (Sonic the Hedgehog)
- Unknown Train (Train Tishka)
- Dr. Fetus (Super Samson Herms)
- Mewtho or Makuta (Takua, Jaller & Hahli Productions)
- Behemoth (Nitrome)
Counterparts (Magical Island Version)
- Diesel 10 (Thomas the Tank Engine and Friends)
- Smelter (TUGS)
- Cabot (Theodore Tugboat)
- Smithy (Super Mario Bros.)
- Gerald Robotnik (Sonic the Hedgehog)
Counterparts (Connor and Caitlin Version)
- Devious Diesel (Thomas the Tank Engine and Friends)
- Bowser (Super Mario Bros.)
- Dr. Neo Cortex (Crash Bandicoot)
Counterparts (Skarloey Version)
- S.C. Ruffey (Thomas the Tank Engine and Friends)