Sorry, that should read Snurre Ironbelly (stupid autocorrect). He's the eponymous big bad from the 1E adventure "Halls of the Fire Giant King", which is part of "Against the Giants" and all the different iterations of that module. He appears on the 5E PHB cover, actually....although I don't think he's appeared anywhere else in the 5E publications. I believe that Chris Perkins did a remake of "Hall of the Fire Giant King" for 4E and Snurre's stats appeared in that, but I am not sure where that adventure appeared. I suppose it was in the online version of Dungeon Magazine.
Eclavdra is the High Priestess of Lolth from the 1E adventure "Vault of the Drow", which is the continuation of the "Against the Giants" series. They're all collected in the epic campaign "Queen of the Spiders". Eclavdra's stats last appeared in the 3E Epic Level Handbook.
Both of them, along with Iggwilv, are characters we used back in the early days of my group's D&D experience. Snurre lost an eye to one of our PCs and then fled, and Eclavdra had to flee from the PCs after they defeated her forces. My current campaign continues a lot of what we did back then, so I have brought these characters back into he fold.
Iggwilv was never meant to be fought back then, and I am not aware she ever really had any official stats, but I am sure she was statted out in the 3E days and I just don't know where.