Sean Parker, the billionaire creator of Napster and co-founder of Facebook, is marrying Alexandra Lenas on June 1 in a somewhat unusual wedding: what the New York Post describes as a "medieval-themed costume party." Parker and Lenas, who have a baby daughter together, will wed in California's Big Sur forest during an entire weekend of festivities. "Guests will each get their own costumier," a source says. "There is a chance the wedding could end up looking like an episode of Game of Thrones." Parker, who was famously portrayed by Justin Timberlake in The Social Network, is apparently known for his love of costuming; in 2010, he dressed as Timberlake for Halloween, with Lenas as Britney Spears.