Felix the Cat is an anthropomorphic talking black cat created by Pat Sullivan and Otto Messmer who first appeared in the black and white silent cartoon Feline Follies in 1919, almost a decade before Mickey Mouse's debuts. Over the years, the characters starred in many theatrical shorts, cartoon series, and even an animated movie, all of them expending the characters universe; one the most noteworthy addition to the character was his trademark Magic Bag, which is able to turn into anything he wants.
He however never managed to reach the same popularity as Mickey Mouse or Bugs Bunny and slowly faded into obscurity. He however remains to this day an iconic character from another time, and still occasionally appears in some form here and there, often as a throwback to his original time period.
Felix the Cat as a character actually appears in very few rips. He is the de facto representation of the Puzzle Room meme following the Puzzle Room - Kirby Planet Robobot debacle, which was a reference to Vinesauce Joel's reaction to a Sega Genesis bootleg port of a NES Felix the Cat game.
He appears in a couple of rips referencing the original incident, in the cover of a second playlist (Baby Felix Halloween), in the crossover song This Is Halloween - Kingdom Hearts II, and also as a cameo in Title Theme & Ending - 7 GRAND DAD.
Felix the Cat was one of the Figments materialized into the real world by the Voice Inside Your Head in "Prologue", before being immediately taken by the Patrol-Bots. As of "Loves the Ladies", he is still in captivity.
"Comeback Crisis" portrays Felix as being possessed by Halloween Spirit, a sinister form of Christmas Spirit that forms due to SiIva's nightmares, and dying when Wood Man wakes SiIva up, dissipating the Halloween Spirit. However, it is currently unclear as to whether this episode, and thus any of these events, is canon.