Wendy's has a cute little girl with pigtails, Burger King has... well, a Burger King, and McDonald's has a menagerie of characters who romp about in a magical burgery world called McDonaldland, and it's as weird as you barely remember. McDonald's began with only a clown, but as the brand expanded to new markets - and appealing to children became the name of the game - the company branched out with more characters than could fit in a McDonald's ball pit.
The McDonaldland characters were zanier than those of the other franchises, and were featured not only in commercials and toys, but also in an animated series called The Wacky Adventures of Ronald McDonald. The characters continued to serve their burger masters from 1970 until 2003, when the majority of them were retired, making them some of the longest-lasting characters in any non-cereal advertising campaign.
While you might not think of comparing the convoluted character menagerie of McDonaldland to a cast of characters like those in the MCU, let's not forget that Star-Lord referred to Thanos as "Grimace," ultimately tying the two together for all eternity.