Axl

Axl was a rat that Ray Palmer gave Mick Rory for Christmas. He is seen many times on the Waverider after his first appearance, and in Doomworld as a test subject for Ray. In Amazing Grace, his name becomes an aberration, being changed to Josh Groban due to R&R never becoming popular, however, the aberration is soon fixed. Axl later dies from ingesting poison, and as an effect of the Death Totem, his ghost roams the Waverider until his final moments with Mick cause his ghost to be released.

Discovery
Axl was found in the vents of the Waverider by Ray Palmer who then, gave it to Mick Rory for Christmas.

Rewritten reality
In a reality made by the Legion of Doom, Axl was Ray Palmer's test subject.

Behind the Scenes

 * In the slightly altered reality where Elvis Presley was committed to an asylum, Axl's name was Josh Groban. Josh Groban is both an actor and singer famous for winning several Platinum awards.