Eberhardt is a character who appears in "Henchman." He lives in a cabin in the middle of a swamp, where he spends his time playing the piano. He thinks Marceline will suck his blood, but she only sucks the red out of his tie. He then thanks her for making his tie white, saying it is "so beautiful." Later, Marceline asks Finn, "You thinkin' about how that guy's bow tie sorta looked like a bra?"
There are numerous pictures on the walls of Eberhardt's house depicting him with a much taller female with similar hair and facial features. He says he was married once, so this is likely his former wife, who either passed away or divorced. Either way, it is likely their relationship did not end well, as just reminiscing about it is enough to make Eberhardt shed a tear.
He has a greenish suit and a very big red bow-tie (which turns white after Marceline sucks the red out of it) and two medals on the bottom of his suit, possibly indicating veteran status. He has long dark hair and orange wrinkly skin.