Mark Rein·Hagen (often written Rein-Hagen) is a role-playing, card, video and board game designer, best known as the creator of Vampire: The Masquerade and its associated World of Darkness games. Rein·Hagen is also one of the original two designers of Ars Magica along with Jonathan Tweet.
A founder and owner of White Wolf he sold his half of the company in 2007 and left the gaming field. Rein·Hagen served as a writer and producer for Kindred: The Embraced, a TV show based on Vampire, produced by Aaron Spelling and shown on Fox TV. Kindred was cancelled, however, following the death of its star Mark Frankel.
As a side project independent of White Wolf Game Studio, Rein·Hagen founded Atomoton Games and created Z-G, the first collectible action figure game. Despite the high production value and plans for numerous tie-ins, the game failed to find a market and sank the company.
Following the demise of Atomoton Games, Mark briefly pursued a farming career in central California, raising poultry for export to Asian markets.
As of mid 2008 he was purportedly living in Tbilisi, Georgia with his wife and child during the 2008 South Ossetia War, Rein-Hagen was evacuated with other US Citizens living in Georgia and started the now defunct site sosgeorgia.org to help track what was happening. The site can still be viewed using the waybackmachine.org website as of 2011.