In one Sunday strip, Garfield tells Jon he wants lasagna for dinner, but Jon, being unable to understand Garfield's thoughts (in this strip, anyway) suggests things like steamed rice. Garfield, furious, walks away and comes back with ingredients, throwing them in Jon's face. Jon FINALLY decides on lasagna.
In one strip, Jon deliberately denies Garfield kitty treats because "life isn't fair." Garfield's response? Yank one of Jon's neck hairs.
Jon has one in an early strip where gets Garfield to take his bath. He tries to wrestle Garfield into the bath, and when he fakes defeat, Garfield jumps off the table and into a second tub of water.
In the prime-time TV special Garfield In the Rough, an escaped panther threatens the life of Jon and Odie. Garfield, who ran up a tree in fear, has a sudden Papa Wolf moment, dives from the tree onto the panther's back, clawing away at it with stock sound effects of an enraged housecat. He doesn't actually defeat the panther, though he does buy park rangers some time to tranquilize it without anyone getting hurt.
Doubles as a Crowning Moment of Heartwarming that Garfield would actually risk his life for Jon and Odie, especially since a few of the jokes in the comics and animation are about Jon specifically asking Garfield if he would do just that, and getting turned down.
In the Halloween Special, as Garfield and Odie jump into the lake to escape the evil pirate ghosts, Garfield almost immediately sinks under and is swept away by the current, as he can't swim. Odie immediately dives underwater to find him and pulls him to safety. This doubles as a Heartwarming Moment, because he could have chosen to just save himself, but he cares too much about Garfield. To add to the heartwarming, Garfield, who was originally going to take all of Odie's trick or treat candy, states that he can keep it and have half of his own. Garfield gave up some of his food as a thank you.
He does it in the sequel as well, and that time seemed even more-awesome because the Big Bad had Liz at gunpoint up until a few seconds prior. Also note that in both movies, Jon simply needs to deck the Big BadONCE to render him unconscious.