Tonky

Tonkii is a Beast-type evil-god who Kirito saves in Jötunheimr. Later, he forms a friendship with Kirito and Suguha, which turns him into an NPC, and allows them to ride on its back.

ALfheim Online
The first thing that Kirito and Lyfa notice after dropping into Jötunheimr is two evil-god monsters fighting from a distance. It was clear that the Beast-type evil god (Tonkii) was losing against the human-type evil god. Kirito decides to help the beast by drawing the human-type god into water. The beast-type looked like a mix between a jellyfish and an elephant so Kirito assumed that it had a affinity for water. After defeating the human-type evil god, the beast-type evil god lifted Kirito and Lyfa onto its back and traveled to the center of Jötunheimr. While traveling, Kirito decides to name it Tonkii, named after a childhood book that he read when he was younger. After arriving, Tonkii went into hibernation mode and quickly recovered its health points. Kirito and Lyfa get off of its back but aid it when it is being attacked by a player party. Once at low hp, Tonkii awakens and transforms into a flying beast. Kirito and Lyfa sucessfully scatter the remaining players and Tonkii lifts the two up onto its back and flies to the top of Jötunheimr. Leaving them in a staircase which took them to Aarum through a secret passage.

Caliber SS
In an attempt to retrieve Excalibur, Kirito leads a group through Jötunheimr. They ride on Tonkii's back to get to the location to begin the quest.

After obtaining the sword, Tonkii saves the group when they are falling from the top of Jötunheimr into what seemed like a bottomless hole.