I have found, as an evergreen referee, that I'd much rather pilot NPCs than play a proper character in an ongoing campaign. I've mentioned this before, but as I consider today's topic, it is especially relevant.
NPCs are skeleton keys to the campaign world for referees. They are direct representations of tropes, themes, needs, and wants that you (if you're running a game) want to convey to the players to make the setting come alive. I'd rather spend three hours playing a dozen+ NPCs than a single, titular character. I've learned this over time. It remains my staple experience in adventure games.
This is brief preamble for my sharing with you my Meta NPCs. That is, my favorite NPCs that show up in just about all of my games regardless of genre or setting (tailored to fit, as necessary). I've lived with these characters in my head for years now, and they always bounce around when I daydream some idea or another. Some were spawned originally in my 5e games, and others elsewhere. All of them have been a blast to drop in and out of my various tables.