Barney is a "barn cat" on the Arbuckle farm that Garfield met. He is a blue-gray cat with a bent tail. Garfield was unaware of where he lived.
He was put into a draft strip available to read in Garfield: Survival of the Fattest.
Grafield is a cat that Garfield once encountered. He is a reddish-orange cat, very much like Garfield, being fat and lazy. His name is almost identical to Garfield's, with the second and third letters being swapped. He appeared to be more positive in personality than Garfield.
Maynard is a gray cat from the "Temporary Cat Services". He once filled in for Garfield (who was taking "a little personal time"), having been bribed with food. Jon was not thrilled with his appearance.
Smiley is a cat who got electrocuted while tiptoeing over an electric fence. As a result, his face is always stuck in a big smile (hence his name) with his head tilted skyward.
Smiley appeared in a draft strip featured in Garfield: Survival of the Fattest.