E-122 Psi was an E-100 Series robot.
Psi was the penultimate E-Series robot created by Dr. Eggman. At some point it surrendered to E-102 Gamma in Deerwood Forest. Gamma was conflicted about having to destroy his brother, but he ultimately decided to do so in order to free Psi's Mobini battery, logging the new emotions of suprise, pity, and a new variant of regret into his databanks. (ASUB)
- Psi was never formally introduced in the comics, but his fate was revealed in the (now defunct) Sonic Universe blogs.