[kupoartist]

David Hayter has few Anime roles (Though to his credit, they're often quite big, e.g: super-hunk Tamahome in Fushigi Yugi and Lupin III in Castle of Cagliostro), but Spike isn't one of them: https://animenewsnetwork.com/encyclop...le.php?id=8759
(weird that he sometimes goes under an alias - or is David Hayter the alias?).

Steven Jay Blum plays Spike in the English CB: https://animenewsnetwork.com/encyclop...le.php?id=4832

David Lucas appears to be no one in particular (in CB), playing "Weapon Shop Owner" and "Yuri Kellerman" - https://animenewsnetwork.com/encyclop...ple.php?id=539

And just for the sake of it: The Japanese VA for Spike - https://animenewsnetwork.com/encyclop...le.php?id=1009
(that's a lot of roles, even those for non-anime!)

A full cast list for Cowboy Bebop (Jap and then Eng) can be found: https://animenewsnetwork.com/encyclop...nime.php?id=13

Edit: so to summarise, David Hayter doesn't play Spike in CB, Steven Jay Blum does. Steven Jay Blum is also apparently not the same person as David Lucas.