The Axolotl is a powerful extradimensional creature who is mentioned by Bill Cipher while being erased by Memory Gun during the Weirdmageddon. It is later mentioned by Bill once again on Journal 3, and only makes his first appearence in "Dipper and Mabel and the Curse of the Time Pirates' Treasure!: Select Your Own Choose-Venture", when Dipper and Mabel encounter the Axolotl in "the time and space between time and space".
Powers and Stats
Tier: At least Low 1-B
Name: The Axolotl
Origin: Gravity Falls
Age: Unknown (Exists on "time and space between time and space"), likely Inapplicable
Classification: Axolotl, Salamander, Supreme Being, BIG FRILLY and God
Powers and Abilities: Mostly unknown, Resurrection (Bill could supposely come back to life by saying/"invoking" his/her/its name), Memory Manipulation (Erased Dipper and Mabel's memories about him/...), Space-Time Manipulation, and Omnipresence, Omniscience and possibly Omnipotence.
Speed: Omnipresent (Exists on "time and space between time and space")
Lifting Strength: Irrelevant
Striking Strength: At least Low Hyperverse level
Durability: At least Low Hyperverse level
Stamina: Probably limitless
Standard Equipment: Unknown