- "Hold on to your hats!"
- — Dowager Hatt's catchphrase
Mrs. Dowager Hatt is the Fat Controller and Sir Lowham Hatt's mother, Stephen and Bridget Hatt's great-grandmother, and Lady Hatt's mother-in-law. She owns a Dalmatian, which she renamed "Gremlin" after her adventure with Gordon's "gremlins". She is a bit of a thrill-seeker and hates going slow and resting.
In the Driver Perkins segments of the Thomas and the Runaway Kite DVD it is revealed that she also has a parrot named Beaky.
As of the CGI series, Dowager Hatt appears to live near Maithwaite.
- Season 5 - Gordon and the Gremlin
- Season 6 - It's Only Snow (cameo) and Thomas the Jet Engine (cameo)
- Season 9 - Thomas and the Birthday Picnic
- Season 11 - Percy and the Left Luggage
- Season 12 - Excellent Emily (does not speak)
- Season 13 - Percy's Parcel
- Season 14 - Jitters and Japes
- Season 15 - Gordon and Ferdinand, Percy's New Friends (cameo), Edward the Hero, Up, Up and Away!, Stop that Bus!, Wonky Whistle (cameo), Tree Trouble, and Fiery Flynn
- Season 16 - Express Coming Through, Percy and the Monster of Brendam (mentioned), Thomas and the Sounds of Sodor (cameo), Muddy Matters (cameo), and Happy Birthday Sir! (does not speak)
Dowager Hatt with the Fat Controller and her dog, Gremlin
Dowager Hatt among the villagers
Dowager Hatt among the passengers
Dowager Hatt at her birthday
Dowager Hatt with Sir Topham
Dowager Hatt being bounced around inside Annie
Dowager Hatt and her friends
ERTL Dowager Hatt and Mrs. Kyndley