What is Jack Donaghy's formal first name?

Jack Donaghy's formal first name is John.

The character is formally named John Francis Donaghy, although nearly everyone calls him Jack. Alec Baldwin plays the driven NBC and GE executive whose polished confidence, aggressive ambition, and elaborate personal mythology make him one of 30 Rock's central characters.

The name fits the character's Irish-American family background and his habit of presenting himself as more imposing than his surroundings. The show generally uses “Jack,” but “John Francis” appears when the story emphasizes his full identity, family history, or formal status.

This answer is easy to confuse with Jonathan, Joseph, or James because Jack is often used as a nickname for John and because the series surrounds him with many executives whose names begin with different initials. Jack is not short for Jonathan in this case. His daughter with Avery Jessup is named Elizabeth “Liddy” Donaghy, after Liz Lemon.