Gaylen is a posthumous antagonist of 3Below.
However, he became greedy and fearsome with his own power and almost destroyed the planet. Luckily, an ancient 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!"
- According to Aaron Waltke on Twitter, he likes to think of Seklos and Gaylen as "children of Titans - creatures that tapped into their primordial energy, or were perhaps created by them."