Which nursery rhyme character "sat in a corner, eating his Christmas pie"?

The nursery-rhyme character who “sat in a corner, eating his Christmas pie” is Little Jack Horner.

The rhyme continues with Jack putting his thumb into the pie, pulling out a plum, and proudly declaring, “What a good boy am I.” The Christmas pie is therefore a defining image from the traditional verse, not a detail borrowed from another holiday rhyme.

The rhyme circulated in England before its modern wording became standardized. A version was printed in the early 18th century, and later collections helped establish the familiar four-line form. Some accounts connect Jack Horner with a real Thomas Horner, a steward associated with Glastonbury Abbey during the Dissolution of the Monasteries, but that identification is speculative rather than proven.

A common mix-up is with Little Miss Muffet, who sat on a tuffet while eating curds and whey. Jack Horner sits in a corner and eats pie. Another neighbouring detail readers often remember is the plum: it is the object he pulls from the pie, followed by his boast about being good.