Deadite is not an official Storybook Brawl term. It’s the word I use for a Hero/player who has been knocked out of the game but still takes part in a brawl. The term comes from the Evil Dead franchise.
If there are an odd number of players left in the game, one will be matched against a Deadite (symbolised by a blank face). Losing a brawl to a player who has already been eliminated is very embarrassing!
Since playing against a Deadite gives you an advantage, I’m hoping that one day the game will have a Treasure that improves your chance of getting the match-up.