Adam Beach (born November 11, 1972) is a Canadian actor. He is best known for his roles as Victor Joseph in Smoke Signals; Frank Fencepost in Dance Me Outside; Tommy on Walker, Texas Ranger; Kickin' Wing in Joe Dirt; US Marine Corporal Ira Hayes in Flags of Our Fathers; Private Ben Yahzee in Windtalkers; Dr. Charles Eastman (Ohiyesa) in Bury My Heart at Wounded Knee; NYPD Detective Chester Lake in Law & Order: Special Victims Unit; and Officer Jim Chee in the film adaptations of Skinwalkers, Coyote Waits and A Thief of Time. He starred in the Canadian 2012–2014 series Arctic Air and played Slipknot in the 2016 film Suicide Squad. He also performed as Squanto in Disney's historical drama film Squanto: A Warrior's Tale. Most recently he has starred in Hostiles (2017) as Black Hawk and the Netflix original film Juanita (2019) as Jess Gardiner and Edward Nappo in Jane Campion's The Power of the Dog.

Adam Beach was born in Ashern, Manitoba. He is Saulteaux Anishinaabe and has some Icelandic roots through his great-grandmother. Beach spent his early years with his parents and two brothers on the Lake Manitoba/Dog Creek First Nation Reserve at Lake Manitoba. When Beach was eight years old, his mother, Sally Beach, eight months pregnant with a baby girl, was killed by a drunk driver. Eight weeks after his mother's death, the family discovered their father Dennis Beach had drowned near the community. It is unclear whether his death was an accident or suicide.

Adam and his two brothers initially lived with their grandmother; he was with her from age 8 to 12. Five years after their parents' deaths, the three brothers were taken to Winnipeg to live with an aunt and paternal uncle: Agnes and Chris Beach (his father's brother). Adam refers to his Uncle Chris as "Dad".

Beach attended a drama class at Gordon Bell High School. He began performing in local theatre productions and eventually dropped out of school to take a lead role at the Manitoba Theatre for Young People.

Beach has a long list of diverse portrayals. He saw acting as a catharsis and turned to theatre as a venue to express his feelings and tell his own personal stories. At age 18, Beach won a small role in the miniseries Lost in the Barrens, based on the Farley Mowat novel. In the following years, he continued to work in local theatre and guest-starred on television shows such as Walker, Texas Ranger and Touched by an Angel. Shortly afterwards, Beach was cast as a regular on the television shows North of 60 and The Rez. After his performance in Dance Me Outside, he starred in Smoke Signals, which was nominated for the Grand Jury Prize at the Sundance Film Festival. He took a small role in Disney's Mystery, Alaska in 1999 and in 2000 accepted a role in the thriller, The Last Stop. Beach appeared in Helen Lee's The Art of Woo and the 2001 hit Joe Dirt as Kickin' Wing, a Native American fireworks salesman. The producers of Joe Dirt had originally wanted to hire Evan Adams for the parody of his character in Smoke Signals, but accidentally called Beach instead.

In 2002, Windtalkers, starring Beach, was released in theatres; it was about Navajo codetalkers working with the US Marines during World War II. To prepare for this role, Beach spent six months learning the Navajo language. He used this language in his next project, Skinwalkers, based on a novel by Tony Hillerman and directed by Chris Eyre, who had given him his break-out role in Smoke Signals. Between large-scale projects, Beach made small television appearances on such shows as JAG and Third Watch. Also, in 2003, he returned to the character that he first portrayed in Skinwalkers in the movie Coyote Waits, also based on a Hillerman novel. He also made a guest appearance in the hit show The Dead Zone as a Native shaman (in the episode "Shaman").

In 2006, Beach portrayed Ira Hayes in Clint Eastwood's feature film Flags of Our Fathers. During the filming of this movie, both Beach's grandmother and his best friend died. Beach commented, "And if you add those up, there's a lot of emotion. When you're doing a movie, when you let go emotionally, there's nothing to grab onto," he said about the deaths. About playing the part, Beach said, "For me, playing Ira was a meaningful relationship. I would call it – trying to find out how he was, or how he thought and felt". The movie won two Academy Award nominations and Beach was nominated for multiple Best Supporting Actor honours.

In 2006, Beach ran as a candidate to lead his Lake Manitoba First Nation; he was not successful but said he will try again. In 2007, Beach starred in HBO Films' adaptation of Dee Brown's history, Bury My Heart at Wounded Knee. In the film, Beach portrays Charles Eastman (Dakota name Ohiyesa), a doctor, Sioux advocate and author. He explores and expresses the changing understanding of Aboriginal-US relations during the period leading up to the Wounded Knee Massacre.