William George Bunter is a fictional character created by Charles Hamilton

Charles Hamilton (writer)

Charles Harold St. John Hamilton , was an English writer, specializing in writing long-running series of stories for weekly magazines about recurrent casts of characters, his most frequent and famous genre being boys' public school stories, though he also dealt with other genres...

 using the pen name Frank Richards. He featured originally in stories set at Greyfriars School

Greyfriars School

Greyfriars School is a fictional English public school used as a setting in the long running series of stories by the writer Charles Hamilton, who wrote under the pen-name Frank Richards. Although the stories are focused on the Remove , whose most famous pupil was Billy Bunter, other characters...

 in the boys weekly story paper The Magnet

The Magnet

The Magnet was a United Kingdom weekly boys' story paper published by Amalgamated Press. It ran from 1908 to 1940, publishing a total of 1683 issues. Each issue contained a long school story about the boys of Greyfriars School, a fictional public school located somewhere in Kent, and were written...

first published in 1908, and has since appeared in novels, on television, in stage plays, and in comic strips.
Charles Hamilton invented the character for an unpublished story in the late 1890s.