Eilleen Regina "Shania" Twain OC (/aɪˈliːn/ ^ⓘ /ʃəˈnaɪə/ ^ⓘ eye-LEEN ... shə-NY-ə; born August 28, 1965) is a Canadian singer and songwriter. She has sold over 100 million records, making her one of the best-selling music artists of all time and the best-selling female artist in country music history. She received several titles including the "Queen of Country Pop". Billboard named her as the leader of the 1990s country-pop crossover stars.

Twain grew up in Timmins, Ontario, and from a young age she pursued singing and songwriting before signing with Mercury Nashville Records in the early 1990s. Her self-titled debut studio album was a commercial failure upon release in 1993. After collaborating with producer and husband-to-be Robert John "Mutt" Lange, she rose to fame with her second studio album, The Woman in Me (1995), which brought her widespread success. It sold over 20 million copies worldwide, spawned eight singles, including "Any Man of Mine" and earned her a Grammy Award. Twain's third studio album, Come On Over (1997), has sold over 40 million copies worldwide, making it the best-selling studio album by a female solo artist, the best-selling country album, best-selling album by a Canadian, and one of the best-selling albums of all time. Come On Over produced twelve singles, including "You're Still the One", "From This Moment On", "That Don't Impress Me Much" and "Man! I Feel Like a Woman!" and earned her four Grammy Awards. Her fourth studio album, Up! (2002), spawned eight singles, including "I'm Gonna Getcha Good!", "Ka-Ching!" and "Forever and for Always".

In 2004, after releasing her Greatest Hits album, which produced three singles including "Party for Two", Twain entered a hiatus, revealing years later that diagnoses with Lyme disease and dysphonia led to a severely weakened singing voice. She chronicled her vocal rehabilitation on the OWN miniseries Why Not? with Shania Twain, released her first single in six years in 2011, "Today Is Your Day", and published an autobiography, From This Moment On. Twain returned to performing the following year with an exclusive concert residency at The Colosseum at Caesars Palace, Shania: Still the One, which ran until 2014. In 2015, she launched the North American Rock This Country Tour, which was billed as her farewell tour. Twain released her first studio album in 15 years in 2017, Now, and embarked on the Now Tour in 2018. In 2019, she started her second Las Vegas residency, Let's Go! at the Zappos Theater. Her sixth studio album Queen of Me was released in 2023, and she embarked on the Queen of Me Tour in the same year.

Twain has received five Grammy Awards, two World Music Awards, 39 BMI Songwriter Awards, inductions to Canada's Walk of Fame and the Hollywood Walk of Fame, as well as the Canadian Music Hall of Fame and Nashville Songwriters Hall of Fame. According to the RIAA, she is the only female artist in history to have three (consecutive) albums certified Diamond by the RIAA and is the seventh best-selling female artist in the United States. Altogether Twain is ranked as the 10th best-selling artist of the Nielsen SoundScan era. Billboard listed her as the 13th Greatest Music Video Female Solo Artist of all time (42nd overall). According to Billboard Boxscore, she is the highest-grossing female country touring artist with $421.1 million gross from her concert tours.

Twain was born Eilleen Regina Edwards in Windsor, Ontario, on August 28, 1965, to Sharon (née Morrison) of Irish descent and Clarence Edwards. She has two sisters, Jill and Carrie Ann. Her parents divorced when she was two and her mother moved to Timmins, Ontario, with her daughters. Sharon married Jerry Twain, an Ojibwa from the nearby Mattagami First Nation, and they had a son, Mark. Jerry adopted the girls and legally changed their surname to Twain. When Mark was a toddler, Jerry and Sharon adopted Jerry's baby nephew Darryl when his mother died. Because of Twain's connection to Jerry, the media have incorrectly reported that she is of Ojibwe descent. When questioned as to why she chose not to publicly acknowledge Edwards as her biological father for years she said:

My father [Jerry Twain] went out of his way to raise three daughters that weren't even his. For me to acknowledge another man as my father, a man who was never there for me as a father, who wasn't the one who struggled every day to put food on our table, would have hurt him terribly. We were a family. Step-father, step-brothers, we never used that vocabulary in our home. To have referred to him as my step-father would have been the worst slap across the face to him.

She holds a status card and is on the official band membership list of the Temagami First Nation. In 1991, Twain was offered a recording contract in Nashville and applied for immigration status into the United States. At that time, by virtue of her adoptive father Jerry Twain being a full-blooded Ojibwe and the rights guaranteed to indigenous Americans in the Jay Treaty (1795), she became legally registered as having 50 percent indigenous American blood.

Twain has said that as a child she was told by her mother that her biological father was part Cree; his family denies having Cree ancestry but affirmed hearing Twain's mother make this claim. Her confirmed ancestry includes Irish and French roots. Through a maternal great-grandmother, she is a descendant of French carpenter Zacharie Cloutier. Her Irish maternal grandmother, Eileen Pearce, emigrated from Newbridge, County Kildare.