What is the real name of the Fat Controller?

The real name of the Fat Controller is Sir Topham Hatt.

He is the controller of the North Western Railway on the fictional Island of Sodor, overseeing Thomas and the other engines. “The Fat Controller” is his familiar British title, while Sir Topham Hatt is the character’s formal name.

The name was revealed in the Railway Series book Henry the Green Engine, published in 1951. Earlier stories called him “The Fat Director,” but that title changed to “The Fat Controller” as the railway setting reflected Britain’s nationalisation of major railways in 1948.

A common mix-up is assuming “The Fat Controller” and Sir Topham Hatt are separate characters. They are the same person in Thomas & Friends. The books also feature several successive members of the Hatt family who hold the role, although the television series generally presents the character as one familiar figure.