Galen Walton Erso was a human male scientist whose reach focus was on crystals and how they could be used to supply power. Erso particularly focused on kyber crystals, which were used to power the weapon of the Jedi—the lightsaber. The crystals were rare in the galaxy, however, and Erso and a field team went to the planet Espinar in search of rare crystals like kyber crystals. During the six month expedition on Espinar, Erso's life changed forever when he fell in love with their guide, Lyra. The field team failed to find any kyber crystals, but Lyra and Galen left the planet together.
- Catalyst: A Rogue One Novel (First mentioned)
- Catalyst: A Rogue One Novel audiobook (Mentioned only)