Prince Catnip is a "fictional" character Finn and Jake wrote over one of Ice King's Fionna and Cake fanfictions as a punishment for stealing pizzas in a genderbent fanfic I wrote, Nipperpaw
As a character, he's three inches tall, resembles a cat in a blonde hair and fancy suit with no tail and is a proud leader of an entire kingdom of catnip people.
Since they're catnip, they're often attract animals and monster related (and sometimes not) to cats. Because of that, Prince Nip is trained to fight.
He likes soy milk and is sometimes annoyed of the constant screaming of his people due to their paranoid and "high"-ly jumpy nature.
his VO would be The Soup host Joel Mchale
Adventure Time (c) Pen Ward