I played a Fairy Rune Knight/Forge Cleric once. It was really fun, I had the Unarmed Fighting Style, and was focused on Grappling. It was always fun to see the Small Fairy suddenly turn Huge in a single turn, then start beating people's faces in.

I also have a Paladin/Druid/Sorcerer that's surprisingly effective. I took one level of Sorcerer for Shield, then went in as a Wisdom based Paladin.

Then there's my Tabaxi Monk/Barbarian/Fighter who's only ability is having a movement speed of "Yes".