Neptr

Neptr ( or N.E.P.T.R.,  which is an acronym standing for " N ever E nding P ie T hrowing R obot" ) is a robot Finn created solely to prank Jake, appearing in "What is Life?." He came to life when Finn became frustrated that NEPTR wasn't working and threw NEPTR out into the rain where he was hit with a lightning bolt. While this brought him to life, he wasn't fully functional, so Finn took him to Ice King's palace to use the villain's lightning bolts to fully charge him. When he was hit with Ice King's lightning bolt during the resulting battle, part of NEPTR's personality was changed to a desire to collect princesses becoming slightly evil, but he also becomes powered up to full power. He is a pie-throwing robot Finn created and brought to life so he could prank Jake. He usually calls Finn "Creator". He is made up of miniature tank treads, a microwave, a tuning fork, loose wires, a computer chip and a soup can.

NEPTR admires Finn's pranks and has decided to keep Finn as his companion, and has also decided to prank Ice King hardcore. However, he is shown to have some compassion, as he says goodbye to the (unconscious) Ice King before leaving with Finn, causing Ice King to shed a tear. After this, he and Finn throw never-ending pies at Jake.

NEPTR returns in Hot to the Touch, where it is revealed that he was hiding for over 15 months in a game of Hide and Seek and that was accidently forgetten by Finn and Jake.

Appearance
NEPTR is made from pieces of junk stuck together with tape. His components are an electric oven, a soup can, a circuit-board, wires, a tuning-fork and small tank treads possibly from a toy. Finn drew a face on the soup can, intending this to function as the face, but knobs on NEPTR's side became his face when he was brought to life.

Trivia

 * In the end credits for "What is Life?," NEPTR is listed in the credits as "N.E.P.T.E.R.," though it is unknown as to whether this was his intended name, or if the E was included as a mistake.
 * Adam Muto stated that technically NEPTR is half prince, which so far makes him the only prince/half-prince in Adventure Time that isn't imagined.
 * Drawing on that stated above, it is possible that NEPTR is the prince and rightful heir of the Ice Kingdom. Ice King considers him his son, and NEPTR is related to Ice King having been infused with his "private particles".
 * It is unknown where NEPTR gets the ingredients for the pies he makes, possibly generating them spontaneously through magic rather than machinery.
 * NEPTR is much like the monster from Mary Shelley's Frankenstein as both are brought to life by lightning and are made from salvaged non-living parts.
 * NEPTR appears in the episode "Hot to the Touch," where he makes fire-proof robot suits for Finn and Jake.
 * In a sneak peek of "Hot to the Touch," NEPTR's name was spelled "Neptor." It also shows NEPTR's first song, "Working for the Master," and the fact that he has been hiding for 1 year, 3 months, 4 days, and 9 hours.