Ludwig began his career at the age of nine when he featured in a Harry Potter toy commercial , a job that enabled him to sign on with an agent and obtain more commercial work . Later he was cast in movies such as '' Air Bud : World Pup '' ( 2000 ) , '' MXP : Most Extreme Primate '' ( 2003 ) , '' Scary Godmother : The Revenge of Jimmy '' ( 2005 ) , '' Eve and the Fire Horse '' ( 2005 ) , '' The Sandlot : Heading Home '' ( also known as '' The Sandlot 3 '' ) ( 2007 ) . In addition to cinema , Ludwig has also worked in television . He has performed in movies made for television , such as '' A Little Thing Called Murder '' ( 2006 ) , and television series such as '' The Dead Zone '' . Ludwig obtained his leading role in '' The Seeker : The Dark Is Rising '' ( 2007 ) after a " gruelling audition process . " By his count , he had 16 auditions before finally being cast . Ludwig was also in '' Grown Ups 2 '' with Adam Sandler . Ludwig 's next lead role came in the part of Seth – one half of a teenage , alien brother-sister duo – in the film production of '' Race to Witch Mountain '' ( 2009 ) , also starring Dwayne Johnson , the wrestler-turned-actor . Seth is the part originated by Ike Eisenmann in the 1975 original , '' Escape to Witch Mountain '' . The film opened at number one at the box office the weekend that it premiered , with receipts estimated at $ 25 million . Despite his early casting success with '' The Seeker '' , Ludwig indicated in an interview that it was his intention to attend university . In another interview , the actor said that the most challenging thing about filming '' The Seeker '' was trying " to juggle school while filming . " He stated : " My school was n't used to it , and I was n't used to it . It was the most amazing experience , but it was really hard . " In the movie adaptation of '' The Hunger Games '' , Ludwig played Cato , the fierce male tribute from District 2 , the primary threat to the protagonists ' lives during the 74th Hunger Games . The film was released worldwide on March 23 , 2012 . Ludwig won the award for Best Fight on 2012 MTV Movie Awards along with Jennifer Lawrence and Josh Hutcherson , as well as the award for Best Villain at the 2012 Teen Choice Awards . Ludwig released his first single " Liv It Up ( Teenage Wasteland ) " on March 1 , 2012 . In 2013 , he co-starred in the films '' Lone Survivor '' and '' Grown Ups 2 '' . In 2014 , he became a part of the main cast of the Popular TV series '' Vikings '' , playing the character of Björn Ironside , the son of Ragnar Lothbrok and Lagertha . He also appeared in The Band Perry 's music video for " Gentle on My Mind " alongside '' Teen Wolf '' actress Shelley Hennig
2012 MTV Movie Awards
2012 MTV Movie Awards
Alexander Ludwig