Margaret Denise Quigley (born May 22, 1979), professionally known as Maggie Q, is an American actress. She began her professional career in Hong Kong, with starring roles in the action films Gen-Y Cops (2000) and Naked Weapon (2002), before appearing in the American productions Mission: Impossible III (2006), Live Free or Die Hard (2007), Priest (2011) and The Protégé (2021). She portrayed Tori Wu in the dystopian science-fiction action film Divergent (2014), and reprised her role in the sequels, Insurgent (2015) and Allegiant (2016). Q starred in the title role on The CW action-thriller series Nikita (2010–2013), and also had a main role as FBI Special Agent Hannah Wells in the ABC/Netflix political thriller series Designated Survivor (2016–2019). She provided the voice of Wonder Woman on the animated series Young Justice (2012–2019). In 2025, Q began starring in the lead role of Detective Renée Ballard on the Prime Video series Ballard, a spinoff of the television series Bosch: Legacy.

Margaret Denise Quigley was born and raised in Honolulu, Hawaii. Her mother is Vietnamese and her father is American of Polish and Irish descent. Her parents met while her father was stationed in Vietnam during the Vietnam War. She has four siblings. She was raised Catholic. She became a practitioner of Buddhism.

She attended Mililani Waena Elementary School and Wheeler Intermediate School. At Mililani High School, she was on the cross country, track and field, and swim teams. She won the student title of "Best Body" senior year, and graduated in 1997. She won an athletics scholarship to a private university and intended to study veterinary science; however, her family was unable to assist her financially. She left Hawaii at the end of one school year in hopes of earning enough money to resume at the beginning of the next one.

At a friend's suggestion, Q began modeling in Tokyo, Japan at the age of 17, before making an unsuccessful move to Taipei, Taiwan. She tried again in Hong Kong, where she began using the stage name Maggie Q because the locals could not pronounce Quigley properly. She has said it was not easy for her: "I had twenty bucks in my pocket. I mean, I literally did the same thing that my mother did when she left Vietnam... didn't speak the language... had no money." But in Hong Kong, she became a protégé of Jackie Chan, who saw in her a potential action star. His intensive training taught her the importance of professionalism and always doing her own stunts. She later said: "I had never done a day of martial arts in my life when I started in the business. I couldn't even touch my toes."

In 1998, she started her acting career in the TV drama House of the Dragon, which was a huge hit in Asia. In 2000, she made her film debut as Anna in the horror film Model from Hell, and went on to star as FBI agent Jane Quigley in the action thriller Gen-Y Cops that year. Her appearance in Gen-Y Cops impressed Chan so much that he cast her in his films Manhattan Midnight and Rush Hour 2.

In 2002, she starred as martial artist assassin Charlene Ching in the action film Naked Weapon. In 2004, she co-starred with Kelly Hu, Russell Wong and other Asian-American actors in a 30-second PSA produced by Mark Allen for CAUSE USA (Center for Asian Americans United for Self Empowerment), The Least Likely, encouraging Asian and Pacific Islander Americans to register and vote. In 2005, she played Harmony in the German-Singaporean TV mini-series House of Harmony, opposite Fann Wong, and co-produced the animal treatment documentary Earthlings narrated by Joaquin Phoenix.

In 2006, Q made her Hollywood breakthrough as co-star in Mission: Impossible III alongside Tom Cruise. She played Zhen, the only female member of the IMF team. In 2007, she appeared as Mai Linh in the Bruce Willis movie Live Free or Die Hard, the fourth film in the Die Hard series, and as Maggie in Balls of Fury. In 2008, she played fictional Cao Ying, a granddaughter of the warlord Cao Cao in Three Kingdoms: Resurrection of the Dragon, her first ancient Chinese costume performance. That year, she also appeared in the drama/thriller movie Deception starring Ewan McGregor and Hugh Jackman, as Tina, an investment banker who introduces Jackman's character to an exclusive anonymous sex club list. She also stars in the video game Need for Speed: Undercover as the seductive lead character, federal agent Chase Linh, the player's only contact to the Tri-City Police.

In 2010, Q became the lead character, an assassin gone rogue, on the CW series Nikita, based on the 1990 French film of the same name. Since its premiere, she has been incorrectly described as the first Asian American series lead in an American television drama. (Actress Anna May Wong was the first Asian American series lead of an American television series with her show The Gallery of Madame Liu-Tsong, which aired in 1951.) Q received mostly positive reviews for her role in the series. Her character was included in TV Guide's lists of "TV's Sexiest Crime Fighters" and "TV's Toughest Ladies".