(written from a Production point of view)
Christensen studied at the Milwaukee Institute of Art and Design and worked for companies such as Warner Brothers, Paramount Pictures, Quantum Creation FX, Creature Effects, Burman Studio, Masters FX, and Creative Character Engineering.
His credits as conceptual Designer, Concept Artist, Sculptor, and Makeup Effects Artist include feature films such as the action sequel Lethal Weapon 4 (1998), the superhero sequels X-Men: The Last Stand (2006) and Spider-Man 3 (2007), the fantasy film 300 (2006), the thriller The Happening (2008), the comic adaptations Watchmen (2009), G.I. Joe: The Rise of Cobra (2009), and X-Men origins: Wolverine (2009), the science fiction remake TRON: Legacy (2010), the superhero movie Thor (2011, starring Chris Hemsworth), and the scince fiction sequel Transformers: Dark of the Moon (2011).
His television work includes Pushing Daisies, Buffy the Vampire Slayer, Angel, Point Pleasant, The Inside, Firefly, C.S.I.: Crime Scene Investigation, Judging Amy, Miracles, E.R., Chicago Hope, J.A.G., The X-Files, Providence, Gideons Crossing, Popular, Hercules: The Legendary Journeys, and City of Angels.
More recently he worked on the reboot The Amazing Spider-Man (2012), the comic adaptation The Avengers (2012), the science fiction sequel G.I. Joe 2: Retaliation (2012, with Dwayne Johnson), and the reboot of Superman, Man of Steel (2013).