The best Cabal class IMO. Above is the Dust Giants variant.

Ice Reaper Operants (Arc, Solar, Void)
Psion Flayers (Kolar, Vatch, Numoc)
Sky Burners Psion:
Siege Dancers Psion
Blind Legion Psion:
Sand Eaters Psion:
Psion Burner
Unknown Legion
Generic

XBOX 360/PS3 Variants
Psion (DG, SB, SD, BL, SE, UL)
Psion Operants (Solar, Void, Arc)
Psion Flayers (Solar, Void, Arc)

Psions are smaller than all other Cabal morphs, and may be an unrelated
species. Hyper-intelligent, fast and unpredictable, they possess strong
psionic capabilities - including the ability to emit disorienting and
deadly psychokinetic Arc blasts.

Source:http://db.destinytracker.com/grimoire/enemies/cabal

UPDATE 1/6/22 - Added Unknown Legion variant

UPDATE 1/11/22 - Added generic variant

UPDATE 7/23/22 - Added Psion variants based on their adjusted appearances on older console generations

UPDATE 7/26/22 - Fixed back padding for various Psion variants

UPDATE 7/26/22-2 - Added helmet stripe to Unknown Legion Psions

UPDATE 5/9/23 - Adjusted suit color for Unknown Legion