Combine this with the blonde hair and vampirism and we get....
Originally, I thought Crimson Moon was literally just the moon (although I guess he technically is) due to how is always represented by a red moon, but considering he apparently has a sword, he must have limbs to weild it. While Crimson Moon's apperance has never appeared on-screen, we can make some deducations based on other characters, context clues and logical inferences. First, as he seems able to 'manifest' in some way through Arcueid and her being the only True Ancestor we've seen on-screen, we can guess using her appearence. Therfore, it stands to reason he is blonde and pale as she is, and her red eyes would make sense on a guy with crimson in the name. Secondly, Zelretch, who defeated him, apparently resembles (or at least did when he was younger) Jotaro Kujo from Jojo's Bizarre Adventure.
6. Rizo-Waal Strout Rizo-Waal Strout
7. Einnashe/Forest of Einnashe Einnashe
8. Fina-blood Svelten Fina-blood Svelten
9. Altrouge Brunestud Altrouge Brunestud
10. Nrvnqsr Chaos/Louvre Nrvnqsr Chaos
11. Stanrobe Calhin Stanrobe Calhin
12. Unknown Lululily A. Paranodahlia
13. TATARI (See Wallachia, Osiris and Sion variants) TATARI
14. Van-Fem Van-Fem
15. Rita Rozay-en Rita Rozay-en
16. Gransburg's victim/Gransurg Blackmore Gransurg Blackmore
17. Trhvmn Ortenrosse Trhvmn Ortenrosse
18. Enhance Enhance
19. Unknown (possibly Vlov or Zaria) Zaria Offenbaum/Vlov Arkhangel
20. Merem Solomon Merem Solomon
21. Sumire Sumire
22. Unknown (possibly Chromclay Petastructure) Chromclay Petastructure
23. Unknown (possibly Zuckham Eri R) Zuckham Eri R
24. El Nahat El Nahat
25. Unknown (possibly Be'ze) Be'ze
26. Unknown (possibly Agape) Agape
27. Caubac Alcatraz Caubac Alcatraz