Victoria Anne Theresa "Vicki" Peterson Cowsill (born January 11, 1958, in Northridge, Los Angeles, California) is an American rock musician (guitar, vocals).
She described herself as a solo artist in her early years - "I was a kid who brought her guitar to every sleep-over and summer afternoon in the park to play her newest creation to anyone who would listen...". In 1981, she founded The Bangs, later renamed The Bangles, with her sister Debbi Peterson, and Susanna Hoffs.
After The Bangles disbanded in 1989, Peterson played with the Continental Drifters and The Psycho Sisters, in both cases alongside Susan Cowsill. In addition to performing their own material, The Psycho Sisters freelanced as celebrity backing singers (Steve Wynn's Fluorescent, Giant Sand's Center of the Universe), and Peterson has also contributed harmony vocals to recordings by the Hoodoo Gurus, John Doe, Tom Petty and Belinda Carlisle. Additionally, she replaced a pregnant Charlotte Caffey on the 1994-95 Go-Go's reunion tour.
Peterson married musician John Cowsill on October 25, 2003.
In August 2014, after playing together as The Psycho Sisters for more than 20 years, Peterson and Susan Cowsill released their first album, entitled Up on the Chair, Beatrice.