Here are a few scans I took from an old Module, S3, featuring the work of Erol Otus. Otus' lush and atmospheric illustrations were the most evocative of the TSR regulars. Creepy, haunting, buttery renderings without any of the oiled bodybuilders and top-heavy bimbos which populate almost all other fantasy art. Just perfect. WotC could use a man like him today.
This is the best of what I have on hand but hopefully I'll remember to bring in the Cthulhu edition of Dieties & Demigods next week.
Update: in the fifteen minutes since this post, I did a quick google search and found this - the Erol Otus gallery