The name "Ellis" comes from Elijah, Hebrew for "The Lord is my God"
Elis is the first boss in the series to use a "magic circle", the (now scarlet) circle used by many bosses of the Windows series games.
Demon World stage 11~14 BGM is 'Oriental Magician'. But 'Oriental Magician' is Marisa Kirisame's title. Is it coincidence?
Elis is one of the only PC-98 characters whose hair and eyes are not the same color. The only other PC-98 characters with this are Konngara and Shingyoku's "male" form but this is due to the 16-bit color limit the other PC-98 characters have.