Morrigan is voiced by Yayoi Jinguji in most of the games where she was present. The only exceptions in Japanese are Marvel vs. Capcom 3, where she was darrin'd by Rie Tanaka, and her guest appearance in Gunbird 2, where she was voiced by Rei Sakuma, who also voiced her in the Vampire Hunter OVA.
Yumi Touma voiced her in the Dengeki Bunko drama CD.
Scott "Dinobot/Rattrap/Waspinator/Silverbolt" McNeil is his voice in the Night Warriors OVA, and is the only one to reprise their role from the cartoon. His Raptor voice is so well-received to this day that fans are practically demanding him back if Darkstalkers 4 is ever made.
No Export for You: Vampire Hunter 2 (Which features everyone in Vampire Savior sans the characters introduced in that game) and Vampire Savior 2 (Which features everyone in Vampire Savior except Jon Talbain, Rikuo and Sasquatch; plus Pyron, Huitzil and Donovan) never left Japan. We did get Darkstalkers 3 though, which is sort of a mash-up of the two.
What Could Have Been: There were plans for a fourth title in development for the CPS-III system. It is said that Vampire Ace (or Vampire Soldier as it's been called in some places) would have had the core gameplay of Vampire Savior with CPS-III fluid characters. The reasons for the cancellation are unknown.
Every character's final design and story is a far cry from the original intention:
Demitri had a much more minimalist, agile-looking design.
According to the Darkstalkers Graphic File, Morrigan was originally going to be the "cute" character of the series, while all of the sex appeal would go to Felicia.
One of Morrigan's preliminary character designs eventually became Jedah, which is probably where they got the preliminary sibling relation from.
Lord Raptor was supposed to be a vengeful zombie soldier from WWI, hence his birthdate being stated to be in the 1800's—they forgot to change it to reflect the metal image.
Bishamon himself was going to be possessed and not wear any armor.
John Talbain looked more man than wolf and had extremely long claws on one hand.
Sasquatch was an animalistic brute bound in chains.
Victor was a complete lift of Karloff's Monster before being modified into a robot.
Huitzil was a much more modern robot designed for labor. He also had an unfinished super in the first game that was abandoned and never brought back in any of the sequels.
Pyron's looks varied too wildly to do justice in such a small space as this.
Donovan underwent through a large amount of changes:
He was originally a stereotypical Caucasian Vampire Hunter with a broad-brimmed hat that covered his eyes, resembling a masculine Vampire Hunter D or Van Helsing. As designs changed some Asian martial artist themes were added with braided hair and a nunchaku like weapon. Finally we were given the Hinduism/Buddhism themed dhamphyr.
He was also much stronger in the location test build of Vampire Hunter than he was in the finished product. Some of his strengths that were lost include a completely different Blizzard Sword special that caused his ice-covered sword to come crashing down from the top of the screen, a Kill Shred special which had his sword spinning through the air vertically rather than horizontally, thus covering a much wider area, and a Change Immortal EX that would cause huge amounts of chip damage when blocked.
Hsien-Ko's design, though consistent throughout the games, was originally going to be much younger.
In the early stages of development, Lilith was Morrigan's older sister who had the blood of angels mixed in her. She physically resembled Morrigan, the only exception being a pair of angel wings on her head that she hid out of embarrassment.
Q-Bee was a mutated insect with command over other bugs.
Early in development, Jedah was an angelic bishie called "Belial, Jr.", which would have made him Morrigan's adoptive brother.