What was James Potter's nickname in the Marauders?

The story behind the answer

Prongs is James Potter’s Marauder nickname because his Animagus form was a stag, whose antlers have sharp points—“prongs.” Among the Marauders, each nickname matched a form or trait: Moony (Remus Lupin, werewolf), Padfoot (Sirius Black, dog), Wormtail (Peter Pettigrew, rat), and Prongs (James, stag). They became Animagi to accompany Remus safely during his transformations at Hogwarts.

Fun link: James’s Patronus was also a stag, and Harry later produced the same Patronus—an echo of his father. Memory tip: P for Prongs = Points on antlers; Padfoot is the pawed dog (Sirius), while “Stag” and “Antlers” describe James but weren’t his chosen codename.