Gaylen was an ancient Akiridion mentioned in 3Below.
History
Gaylen was a legendary Akiridion who was said to have god-like powers within his life core. At the strength of his core, Gaylen crushed the stars and used its own dust to create Akiridion-5. However, he became greedy and fearsome with his own power and almost destroyed the planet. Luckily, a royal Akiridion, Seklos, built a cannon, and, using all of her life force, defeated Gaylen and hid his core, for it was far too powerful for anyone to have.
In the present day, Akiridions hold Gaylen to a godly status, often exclaiming "What in Gaylen's core?!", "Great Gaylen's core!", or "Seklos and Gaylen!"