Fat and Skinny

Western Animation

 * Nickelodeon has many examples, usually of the "both are silly" variety. In chronological order:
 * Ren & Stimpy.
 * Rocko and his glutinous best friend Heffer in Rocko's Modern Life.
 * Guapo and Fraz, the title characters in The Brothers Flub. A bit unusually for this trope, neither could really be considered a Straight Man.
 * SwaySway and Buhdeuce, the Breadwinners.
 * The Loud House has Clyde's fathers, Harold and Howard McBride.
 * Scratch and Grounder from Adventure of Sonic the Hedgehog.
 * Pinky and the Brain.
 * Katie and Sadie from Total Drama.
 * Total Drama Presents: The Ridonculous Race has returning players Owen and Noah, and cop duo MacArthur and Sanders.
 * SWAT Kats has four such pairs: T-Bone and Razor, Mac and Molly Mange, Burke and Murray, and Mayor Manx and Callie Briggs.
 * Sheriff Blubs and Deputy Durland from Gravity Falls.
 * Robotomy has the main characters Thrasher (skinny) and Blastus (fat).
 * Snips and Snails from My Little Pony: Friendship Is Magic appear to be a fat and skinny pairing.