Big_Bob posted...
Astro Bot
Someone from Baldur's Gate 3
Someone from Metaphor: ReFantazio
Malenia, Blade of Miquella
Doom Slayer
Joker (Balatro)
Seconding these all, as far as newcomers go. Baldur's Gate 3 probably would get 2-3 (or maybe even more) of Astarion, Gale, Karlach, Lae'zel, Shadowheart, and Wyll, since there's no consensus name or appearance for a main protagonist to nominate instead.
In the interest of providing additional suggestions, given that newcomers even comprised 26% (not counting Master Hand or King K. Rool) of 2018's full field:
Clive Rosfield (and maybe Cidolfus Telamon too)
Ichiban Kasuga (Like a Dragon)
Edelgard
Zagreus
Atreus
both Mio and Noah (Xenoblade Chronicles 3)
either Monster Hunter or Rathalos
Sidon
Hero (Dragon Quest XI)
Jin Sakai (Ghost of Tsushima)
either Alphen or Shionne (Tales of Arise)
Arthur Morgan (Red Dead Redemption 2)
EVE (Stellar Blade)
Cat (Stray)
Makoto Niijima
Ciri (due to the Witcher show)
Madeline (Celeste)
Ranked by my estimation of their odds of making a contest, in roughly descending order.
Also want to add to the Sonic characters mention that I think Dr. Eggman would likely return, and Vault Boy could see a similar boon from the Fallout show, as well as Tom Nook from New Horizons, Banjo from Smash Ultimate DLC, Alan Wake from Alan Wake II, and Pyramid Head from the Silent Hill 2 remake. The obvious duo aside (and one other Leon very likely knows about), there're probably a few other games I'm not thinking of that have revitalized veterans absent from 2018.