Let me start by saying, I'm not sure this is in the right category. If it's not, feel free to change it later.
Spawn was considered as a guest character due to an agreement between McFarlane and Namco for the production of
Soulcalibur-themed resin figurines. He was selected for the Xbox version for lack of a more signature or thematic character on that platform, since Tecmo characters (from Dead or Alive) were not viable due to licensing concerns.
This was copied & pasted, so you may have to highlight the text in the quote to see it. Seriously, though, Dead or Alive characters in Soul Calibur II? Now, if you ask my opinion, that would have been awesome. I would have loved to see Ayane vs Taki, or Jann Lee vs Maxi, or something like that. Not that it would become a cross over, like SfVSTekken, or anything like that, necessarily, it probably would've just had Ryu Hayabusa, & they would've given him Raven's moveset. Or would they? Soul Calibur II came out in 2003, Tekken 5 came out in 2004, which makes that statement...debatable. Let me just tell you, though, I copied & pasted that quote from Spawn's wikia page from the Soul Calibur wikia (also, let me tell you that it was from the trivia heading, which I have looked at millions of times, but did not see the DOA part until today! What even.)