Acererak 20
Asmodeus 20
Bargle 18 Demogorgon 21 - Stranger Things knows who is the biggest bad around!
Graz'zt 20
Iggwilv 20
Iuz 20
King Snurre 20
Lolth 20
Lord Soth 20
Orcus 20 Rary 16 - Medium Rary just can't hang with this rogue's gallery
Szass Tam 20
Strahd von Zarovich 21
Tharizdun 20
Tiamat 20
Vecna 19
Venger 20
Vlaakith 20
Warduke 20
Xanathar 20
Zargon 21
On a COMPLETELY unrelated note, wouldn't it be awesome if all the DC Comics supervillains that are cold-based: Mr. Freeze/(Mr. Zero), Captain Cold, Killer Frost, Icicle, Coldsnap, etc. joined up together and formed: