Katerina Alexandre Hartford Graham (born September 5, 1989) is a Swiss-born American actress, singer, dancer, and activist. She played Bonnie Bennett on The CW supernatural drama series The Vampire Diaries (2009–2017). Her film credits include The Parent Trap (1998), 17 Again (2009), The Roommate (2011), Honey 2 (2011), Addicted (2014), and All Eyez on Me (2017). In music, Graham has released two extended plays and four studio albums.

Katerina Alexandre Hartford Graham was born on September 5, 1989, in Geneva, Switzerland, and raised in Los Angeles, California, United States. Her father, Joseph, is of Americo-Liberian descent, and her mother, Natasha, was Jewish (from a family from Poland and Russia). Graham's father was a music executive and the godfather of two of producer Quincy Jones' children. Her paternal grandfather was a UN Ambassador, serving for 40 years in the Netherlands, Sweden, Romania, and Kenya. Graham disclosed in an interview that her father left the music industry to work as a journalist under his father for the UN. Her maternal and paternal grandparents were refugees from the Holocaust and Liberia, respectively, and she credits them as an inspiration for her work as a Goodwill Ambassador for UNHCR.

Her parents divorced when she was 5 years old. During a 2025 episode of the podcast Baby, This is Keke Palmer, Graham revealed she and her father were estranged. She has one half-brother, Yakov, born in Tel Aviv, Israel. Graham was raised in her mother's Jewish religion and attended a Hebrew school.

Graham began her career in the entertainment industry at age 6. Within the following eight years, she appeared in numerous television commercials, including advertisements for Barbie, Edison, K-Mart, and Pop-Tarts. At age 15, Graham caught the eye of choreographer Fatima Robinson, and was asked to perform at the BET Awards as a background dancer for hip-hop rapper Bow Wow. Graham followed her BET Awards appearance with work as a background dancer for Missy Elliott, Pharrell Williams, Jamie Foxx, and choreographers Hi-Hat and Michael Rooney. At age 17, Graham participated in a national marketing campaign to advertise Coca-Cola's soda brand Fanta. Graham appeared in the marketing campaign as a member of the "Fantanas", known as Capri, also known as Strawberry. Graham has appeared in several music videos, including Ying Yang Twins' "Salt Shaker", Akon's "Lonely", Christina Milian's "Dip It Low", Justin Bieber and Usher's "Somebody to Love (Remix)", 112's "What If", John Legend's "Used to Love U", B2K's "Why I Love You", Musiq Soulchild's "B.U.D.D.Y.", Nelly's "Just A Dream" and Diddy – Dirty Money with Usher's "Looking for Love".

In 1998, Graham made her film debut in the remake of The Parent Trap alongside Lindsay Lohan. Graham plays the role of Jackie, a Camp Walden camper. In 2002, Graham made her television debut on the Disney Channel teen comedy series Lizzie McGuire. Graham went on to appear on various television series, including CSI: Crime Scene Investigation, The O.C., Malcolm in the Middle, Joan of Arcadia, Grounded For Life, and Greek. In 2008, she appeared in the musical comedy series Hannah Montana playing the role of a girlfriend to Jason Earles's character Jackson Stewart as a guest appearance for three episodes. Graham has also had well-known supporting roles in films such as 17 Again and The Roommate.

In December 2008, Graham began filming sci-fi/dance film Boogie Town in Los Angeles. However, shooting the film was put on hold that same month due to payroll issues with background performers. In April 2009, principal photography was stopped due to schedule conflicts with some of her co-stars and other projects. The film is a retelling of the tragedy Romeo and Juliet and is set in a futuristic New York City where dance battles are permanently banned. Graham plays the role of Ingrid. The film was set to be released in theaters worldwide October 2011; however, it was set to be originally released in June 2009.

In March 2009, Graham was cast in The CW supernatural drama series The Vampire Diaries based on the book series of the same name. Graham plays the role of Bonnie Bennett, a young witch, which is considered her breakout role. The series premiered on September 10, 2009, to 4.91 million viewers and received mixed reviews for its progression from critics. In May 2012, the series was renewed for the show's fourth season. She took over as the female lead in 2015 after the Canadian actress Nina Dobrev departed for the seventh season. In 2011, Graham won "Choice TV Female Scene Stealer" at the Teen Choice Awards for her role on the show.

In August 2010, The Hollywood Reporter announced that Graham was cast in the Universal Pictures dance drama film Honey 2. The film is a sequel to the 2003 film Honey. The film follows a troubled girl and aspiring dancer who joins a dance crew. The film was released theatrically in selected countries for a limited release and went on to make over US$8 million worldwide. In June 2011, the film was released direct-to-DVD in North America to negative reviews from critics though Graham's performance and dancing was praised. Later that year, Graham starred in the dance-oriented comedy film, Dance Fu, in which she appeared as the female lead.^{[citation needed]}