Magnolia Holst was born in Detroit, Michigan to factory foreman Al Holst and his wife Kate, a retired bookkeeper. Though Al's salary kept the family comfortably sectored into the upper middle class, the Holst family's modest values fostered an upbringing that was largely devoid of frills or excess. When Maggie was seven years old, an impulsive audition for a grape juice commercial sparked a lifelong interest in performance. The less than stellar public elementary school in her district saw both Maggie and her older sister Beth learning at home from their mother, and Maggie was free to pursue songwriting on the family piano as a hobby in her spare time. Both girls developed a love of literature and the arts from Kate, who had once dreamed of playing piano professionally before marriage and work and children claimed her attention.
In 2002, as Maggie was turning eighteen, Beth left the family home to take a teaching job in Santa Barbara, and Maggie, always closest to her sister than anyone else in the family, followed. Hesitant to dream big or take either her interest in acting or music too seriously as a viable career goal, Maggie auditioned only for roles that really stood out to her personally, and the director would later cite the lack of desperation in her youthful personality as the standout feature that led to her being cast in the 2003 film Mirrormask. Humble and quiet by nature, Maggie was not attracted to the Hollywood lifestyle, often preferring to just read scripts instead of auditioning for them, but as time went by and her job as a waitress gradually began to fail to hold her interest, Maggie took the leap and moved into the city to pursue what inspired her.
Her success was marginal, and it did not come overnight. Remembered by fans of Mirrormask as someone with genuine and whimsical appeal, Maggie landed her first major role as the duplicitous magician's assistant in Christopher Nolan's twisty mystery, The Prestige. Playing a character so overtly sensual posed a significant challenge for Maggie, who at the time had only ever had one serious boyfriend, but the Victorian setting and costumes were as wildly appealing to her as the story's intrigue, and Maggie found herself easily identifying with the themes of performance and illusion. The film's success was enough to put Maggie's name on the studio radar, though the whirlwind of promotion and interviewing saw her retreat to her Hollywood bungalow to concentrate on her long-neglected music, accepting only a bit part in bleak western The Assassination of Jesse James by the Coward Robert Ford that same year.
Though her time on set was very short, allowing for only a few quick takes of her role as saloon singer Dorothy Evans, it ended in a friendship with A-list actor Lee Womack, with whom she happily shared a musical kinship in between filming. A year later, she was asked to join him on an independent project that would catapult her into the limelight as both an actress and a talented songwriter. Despite its star power in Lee, Once had humble beginnings. Maggie had never written with a partner before, and the budget was so small that it felt at times as though she were shooting a home movie with her family, but after a glowing Sundance release, the film skyrocketed into mainstream success, earning Maggie and Lee an Oscar for best song and inspiring them to begin performing songs from the film live as the band Gypsy Moth.
When not writing music with Lee, Maggie reveled in the times she was able to keep to herself. The break she wanted to take from acting began as a year in follow up to the film and stretched into two more while she recovered her energy from such an uncomfortable and still unfamiliar lifestyle. Always happiest on stage performing her music, Maggie remains interested in performing arts, still reading scripts as they come her way but with less urgency than ever, now that her main focus is Gypsy Moth's followup to their self-titled album, which she diligently works on whenever Lee is able to take a break from filming.