Technically, an Astral Illithid and former wizard who possesed the "Visage of Marmotilus". But yes, in essence, it's a sex-deprived horny Illithid who realized it's been ages since he got his rocks off.
Thankfully, Elena is proficient in magical items attunement and, ahem*, will have a long and fructiferous "talk" with the guy so the visage's property can be transfered to her.
This scene really makes you think: item attunement with inteligent artifacts is always like that? If true, explains a lot why the party's wizard has to go to a secluded quiet place to "attune" with his wand, staff and alikes lol.
This is a sequel from Lizzie and Klarrie corridor encounter!