Karen O is a pseudonym of Karen Lee Orzolek (b. 22 Nov 1978 in South Korea), lead vocalist with the Yeah Yeah Yeahs and Karen O and the Kids.Her mother is Korean and father is Polish. She grew up in New Jersey, went to Dwight-Englewood high school, and attended Oberlin College, but transferred to New York University's Tisch School of the Arts.

Orzolek has been noted for her sense of fashion. All of her costumes are designed by fashion designer and friend Christian Joy. She is also well known for her outrageous antics during live shows. She is known to often spit water or beer, or sometimes grapes into the crowd.

Her on-stage antics have been compared to punk legends like Iggy Pop and Patti Smith. In 2003 at The Metro, Sydney, Australia (prior to the Yeah Yeah Yeahs' appearance at the Livid festival), she accidentally danced off the stage at a sideshow and reluctantly had to be taken to hospital - a few days later she appeared at the festival in a wheelchair, pushed by Angus Andrew.

She currently lives in Los Angeles, California, in the Silver Lake neighbourhood.