The Patriots’ dominant tight end, known for his combination of size and speed, announced his retirement on Instagram.

Rob Gronkowski, the dominant tight end who helped lead the New England Patriots to three Super Bowl titles in nine seasons while cultivating a goofy, frat boy persona off the field, announced his retirement from the N.F.L. on Sunday.

In an Instagram post, Gronkowski, 29, widely considered one of the most talented tight ends to ever play,