Aaron Himelstein (born October 10, 1985) is an American actor. Following his film debut in High Fidelity (2000), he played the younger version of Austin Powers in the spy comedy film Austin Powers in Goldmember (2002). He subsequently appeared in several films such as All the Boys Love Mandy Lane, Fast Food Nation (both 2006), Remember the Daze (2007), and The Informers (2008). Himelstein joined the Marvel Cinematic Universe, playing the role of Cameron Klein in Captain America: The Winter Soldier (2014), and Avengers: Age of Ultron (2015).

On television, he had a recurring role as Friedman on the CBS fantasy family drama series Joan of Arcadia (2003–05), and provided the voice of Desna on the Nickelodeon animated action fantasy series The Legend of Korra (2013–14).

Himelstein was born on October 10, 1985, in Buffalo Grove, Illinois, the son of Susan (Maloney) and Robert "Bob" Himelstein.^[1][2][3] He is a close friend of Joan of Arcadia stars Michael Welch and Chris Marquette. He and Welch had known each other for several years but they did not become good friends until the series began in 2003.^[4]

He dated Remember the Daze co-star Leighton Meester, after meeting in 2007.^[5]