Warlock (Eldar)
Warlocks are Eldar psykers. Unlike Farseers, who specialize in divination and typically follow the path of the Seer for their entire lives, warlocks were at one point on the Path of the Warrior, who switched to the path of the Seer. Due to this mixing of psychic potential and warrior background, warlocks apply their psychic powers more towards direct combat, rather than the supporting style application used by Farseers.
They are often seen accompanying Eldar Guardians as squad leaders and may even lead parts of a warhost like a field officer. Some specialize in leading Wraithkind, and these are called Spiritseers, and are typically found accompanying Wraithguard around to allow them to act faster (As Wraithguards are souls, they aren't very fast to act on their own. Thus, commonly needs direct guidance). They can also make up a Seer Council, which is basically a 10-elf squad of warlocks that serve as a Farseer's retinue, where their duties range from keeping the Farseer safe while in combat, to assisting the seer in casting certain spells.