Ia there any cult that worships Illithids in the Forgotten Realms?

Hi there!

I'm planning to create a cult in the Forgotten Realms thar worships Mind Flayers, but I don't know if there's any already of it would make sense lorewise.

Could you help me, please?

Thanks in advance.

I don't know of any prominent ones in the lore, likely because Illithids care about humanoid opinions of them about as much as the average person cares what cows think of them. Their MO is aimed at direct psychic domination, so they don't need the artifice of rituals and ceremonies. That said, when they're still in the "covert infiltration" phase, I could see going Lovecraftian with a cult/sect/what have you forming to draw in victims. If you have access to it, Volo's has a section on Illithids that should outline a basic infiltration strategy. Giving it a "culty" vibe probably wouldn't take much.