The best replacement for witch king is lich king.

The best alternatives to witch king are rated as following:
★★★★★  lich king
★★★★★  sauron
★★★★  gandalf
★★★★  eowyn
★★★★  balrog
★★  smaug
★★  saruman
★★  aragorn
★  radagast
★  elrond
★  galadriel
★  mouth of sauron
★  glorfindel
  agandaur
  gandalf stronger
  king of the dead

Your alternative for witch king is not listed? Suggest!
Speaking about witch king, one probably shouldn't forget about bfme2.

Other search terms related to witch king and their ratings are:
★★★★★ bfme2
You have in mind a companion for witch king and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of witch king in all years. Click on graph for more.
witch king
lich king
sauron