Yūki Kobayashi is a Japanese voice actress and singer born on February 5, 1982, in Tokyo, where she remains active in the industry. Prior to voice acting, she worked as a magazine model before beginning her voice acting career in 2003. She is affiliated with the talent agency Holy Peak.

Her career gained early momentum with her first leading role as Tadamichi Aoba in Dan Doh!! in 2004, followed by her portrayal of Setsuna Sakurazaki in the Negima! series beginning in 2005. Over the years, she has built an extensive filmography across anime, video games, and music. Among her most recognized anime roles are Ayame Sarutobi in Gintama, Sasha Braus in Attack on Titan, Luka Urushibara in Steins;Gate, Dan Kuso in the Bakugan Battle Brawlers franchise, Kaere Kimura in Sayonara, Zetsubou-Sensei, Mariya Shidō in Maria Holic, and Charlotte Roselei in Black Clover. She also voiced the role of Committee Chairman in the series Kämpfer. Her work extends to video games, where she is known for voicing Lucina in the Fire Emblem series, Katsuragi in the Senran Kagura series, and Enkidu in Fate/Grand Order.

In addition to voice acting, Kobayashi has pursued a music career. She debuted as a singer in 2007 with the single Sora no Kotoba, which served as an ending theme for Saint October. In 2008, she released her first album, YOU&YU, and the mini-album ROCK YOU!!. She formed the musical group Crush Tears in 2010. Her solo singles include HANAJI, used as the opening theme for Maria Holic.

Kobayashi received the Best New Actress award at the 2nd Seiyū Awards in 2008. She announced her marriage on December 29, 2017.