Adventure Time Season 1 Episode 1: Finn and Jake rescue princesses from the Ice King
Adventure Time Season 6 Episode 43: Finn goes into space to stop a lovecraftian-esque monster (who was previously Gunther) that is trying to absorb the powers of an incoming Catalyst Comet, which comes every 1000 years to bring change to the earth and the people on it. Finn is revealed to be a cosmic entity who came to Ooo as a Catalyst Comet and regenerated several lifetimes to who he is today. He experiences an existential crisis with the new Comet who tells him he can leave behind his material body and ascend into a higher plane of existence where he can leave behind every trouble that is tying him down to earth, to leave behind all the pain and torment of the past few seasons caused by the loss of his arm, his sword, Jake nearly dying, his love life, his father’s ignorance, etc. He declines the offer to the new form of existence because he accepts all the trials of mortal life and the work he put into it, and is not ready to leave it behind.