The original Xbox controller was nicknamed the Duke because of its large size.
The controller shipped with the first Xbox in Japan and North America and was noticeably larger than many contemporary gamepads. Its dimensions and weight led players to call it “Duke,” a nickname associated with Microsoft executive Brett Schnepf, who reportedly had that nickname.
Microsoft later introduced the smaller Controller S as the standard controller in Japan and eventually in other markets. The Controller S retained the same basic button layout but used a more compact shape that many players found easier to hold.
The Duke name is sometimes confused with the Controller S because both belong to the original Xbox generation. Microsoft later released a modernized Duke controller for Xbox One and Windows, preserving the large form and original layout while adding contemporary functions.