Jake the Dog is a fictional character and one of the main cast in the American animated television series Adventure Time created by Pendleton Ward. He is voiced by John DiMaggio. The character made his debut in the original pilot. Jake is Finn’s best friend and adoptive brother. He is a shape-shifting dog who is in his 30s in “magical dog years”. He was conceived by Joshua and an extra-dimensional creature and as a result, Jake can stretch, shrink, or mold any part of his body to any shape and almost any size, ranging from becoming gigantic to becoming incredibly small. He acts as a confidant and mentor to his energetic brother, though has a tendency to give somewhat questionable advice. Jake has a laid-back attitude in most situations, but loves adventure and will eagerly fight when he needs to. His powers help Finn considerably in combat and transportation, but are also sometimes used as nothing more than jovial forms of expression. Jake is in a relationship with Lady Rainicorn voiced by Niki Yang; they have five children together as seen in “Jake the Dad”. He met Lady in the pilot episode and is quite skilled at playing the viola, which houses a worm called Shelby.