Yūko Kobayashi is a veteran Japanese voice actress and narrator born on February 6, 1961, in Tokyo. She is affiliated with the talent management firm 81 Produce. She is married to fellow voice actor Mitsuaki Hoshino.

Kobayashi made her debut as a voice actress in 1983, with her first role being Kaede in the television anime Tokimeki Tonight. The following year, she landed her first leading role as Yū Hazuki in the series Victory Volleyball.

Kobayashi is known for a wide array of roles across several decades. One of her most iconic and long-running characters is Washū Hakubi (also known as Washu Fitzgerald Kobayashi in Magical Project S) in the long-running Tenchi Muyo! franchise, a role she has played consistently since the early 1990s in various OVAs and television series, including the 2016 series Tenchi Muyo! Ryo Ohki. Another of her most prominent roles is Shigeru (Shigeru Ōkido) in the Pokémon anime series, a character she has voiced for many years.

Her extensive filmography demonstrates significant range. She has taken on roles in mecha anime such as Junko Jenko in Mobile Suit Victory Gundam and Sho Tachibana in Getter Robo Go. In fantasy and adventure series, she has voiced Rapier in Maze, Bella in Montana Jones, and Mirei in Stainless Night. She also played Rainy (or Rainey) in the Pururun! Shizuku-chan series and Winnie in Adventures of the Little Mermaid. Her work includes roles in magical girl and sports anime, such as Yuri in Shiroi Koibito, Yumiko Kanō in Davide no Hoshi, Joanna in Shin Davide no Hoshi: Inma Densetsu, and Yu Hazuki in Attacker You!.

In addition to television and OVA work, Kobayashi has also been active in film. A notable early role was the senior witch in Hayao Miyazaki's Kiki's Delivery Service. She has also contributed to dubbing foreign films, such as providing the Japanese voice for Wednesday Addams in The Addams Family movies. Beyond acting, she has worked as a sound director, notably on the animated film Gekijōban Dōbutsu no Mori.