Check Out This Beefed-Up CR17 Strahd!
EN World member dave2008
maintains what is, in my opinion, one of the most useful, fun, and interesting threads on the whole forum. His 5E Epic Monster Updates
thread contains dozens of gods (of the greater, intermediate, lesser, and demi flavours), primordials, demon princes, archdevils, dukes of hell, aberrations, abominations, constructs, dragons, elemental lords, arch-fey, monstrosities, and undead. While the thread is great to read at any time, he's just added a beefed-up CR17 version of Strahd von Zarovich (he's CR15 in Curse of Strahd
). You can see it below, but click on the image and check out all of his epic monsters, as well as his 5E Epic Characters thread