In Nazi Zombies there are the four playable characters, Dr. Edward Richtofen, Takeo Masaki, Tank Dempsey and Nikolai Belinski. I searched the internet this is what I found on people vaguely related to these characters.

Takeo Masaki

Takeo Yasuda was an Imperial Army General that took an interset to nuclear physics, specifically for energy releases through nuclear fission.
info here - http://en.wikipedia.org/wiki/Takeo_Yasuda

Dr. Edward Richtofen

Manfred von Richtofen was an German Fighter Pilot, most well known as Der Rote Baron (The Red Baron) and shot down 80 fighter pilots.
info here - http://en.wikipedia.org/wiki/Manfred_von_Richthofen

This is the most I found it vaguely interesting and I hope you did too.

hmmm.....good find......but i think they made the characters on their own...