Helena Mattsson

Mattsson was born and raised in Stockholm, Sweden. Her younger sister, Sofia, is also an actress. She began acting at a young age, performing in plays, musicals and concerts. She studied acting at the Södra Latin upper secondary school in Södermalm, which she credits with giving her the confidence to pursue her chosen career. Mattsson had early roles in Wild Side Story and other cabarets in Stockholm. She moved to London, England, as a teenager to attend theatre school.At age 19, Mattsson moved to Hollywood to audition for a TV series. Her planned short visit became permanent after she won a role the unsold 2004 TV series pilot Sweden, Ohio. Mattsson's accent initially held her back: "When I started working, my thick Swedish accent lost me a lot of roles. A defining point in my career definitely came when I started to lose it. I was able to play more American roles at that point, and my career took a turn for the better." At the same time, Mattsson made her screen debut appearing in the Swedish slasher film, Drowning Ghost, and later guest-starred on American television shows CSI: NY, CSI: Crime Scene Investigation and Cold Case. Mattsson also appeared in the music video of Primal Scream's "Country Girl" in 2006.

In 2007, Mattsson starred in the science fiction action thriller film, Species: The Awakening, portraying Miranda, an alien/human hybrid. The following year she starred opposite Mischa Barton in the drama film You and I about Russian pop-band t.A.T.u.. The film premiered at the Cannes Film Festival in May 2008 and was released in the United States on 31 January 2012. In 2009 she co-starred in the science fiction action film, Surrogates. On television, Mattsson made guest appearances on Two and a Half Men, Rules of Engagement, Legend of the Seeker, NCIS: Los Angeles and The Mentalist. In 2010 she appeared in a minor role in the superhero film Iron Man 2 and had a recurring role in the ABC series Desperate Housewives as Irina Kosokov. She later had three episode-arc in the CW action series, Nikita as Cassandra Ovechkin.

In 2012, Mattsson starred alongside Gary Oldman and Christian Slater in the action film, Guns, Girls and Gambling. Later that year, she had a series regular role in the ABC supernatural horror series, 666 Park Avenue. The series was canceled after single season in 2013. She later had a recurring roles in the ABC series Betrayal in 2013, and Mistresses in 2014. Also in 2014, Mattsson appeared in two episodes of FX crime series, Fargo, and in 2015 played the female lead in the Hallmark Channel romantic comedy film, Win, Lose or Love. From 2015 to 2016 she had a recurring role in the FX horror series, American Horror Story: Hotel. She appeared in a beaver costume in a Nespresso television commercial titled "Training Day" that also featured Danny DeVito and George Clooney in 2016.

In 2016, Mattsson starred alongside Reza Sixo Safai in the action crime film, The Loner, the film received positive reviews from critics. She later appeared in a number of direct-to-video releases, such as Code of Honor (2016) and Smartass (2017). In 2018, Mattsson played Swedish actress and model Britt Ekland in the HBO biographical drama film My Dinner with Hervé about Hervé Villechaize. Also that year, Mattsson starred alongside her younger sister Sofia in the Lifetime television thriller film My Husband's Secret Wife. She later appeared in several other Lifetime movies: The Perfect One (2018), Neighborhood Watch (2018), Her Deadly Reflections (2019), Swipe Right, Run Left (2019), and Murder in the Vineyard (2020). From 2021 to 2022, Mattsson had a recurring role in the ABC police drama series, The Rookie. In early 2022, she temporarily replaced her sister Sofia Mattsson in the role of Sasha Gilmore on the ABC daytime soap opera, General Hospital.