Viggo Peter Mortensen (born October 20, 1958 in New York City) is an American theater and movie actor, a published poet, musician, photographer and painter. His Danish father and half Norwegian American mother met in Norway. He has a son, Henry Blake, with his ex-wife Christine "Exene" Cervenka of the band X.

He is best known for his role as Aragorn in Peter Jackson's The Lord of the Rings film trilogy. He was a last-minute replacement for the role, and wouldn't have taken the part if it hadn't been for his son's enthusiasm for J. R. R. Tolkien's trilogy. With part of the money he received for the film he founded the Perceval Press publishing house — named for the knight from the legend of King Arthur — to help other artists by publishing avant-garde works that might not find a home in more traditional publishing venues. He has spoken out against militarism and U.S. foreign policy.