Megumi Toyoguchi is a Japanese voice actress and narrator affiliated with the talent agency 81 Produce. She was born on January 2, 1978, in Machida, Tokyo.

Her interest in becoming a voice actor began in her second year of high school, inspired by her fandom of voice actor Tōru Furuya. After graduating from high school, she enrolled in the Nihon Kogakuin college. Although she initially wished to study voice acting, she instead graduated from its Department of Acoustics and Arts after her family expressed opposition. Her studies there, which included training in radio program production, helped her develop the conversational skills for which she would later become known. While still a student, she won the "Mars Girl" audition for the radio program Hiroi Oji no Multi Heaven, which led to her debut and, through her co-star Shigeru Chiba, her introduction to 81 Produce. She made her anime debut in 1998, voicing the title character in Alice SOS.

Toyoguchi is recognized for her wide vocal range, portraying a diverse array of characters. This includes energetic and cheerful girls like Hikari (Dawn) in the Pokémon anime series, a role she played from 2006 to 2010; elegant women; and more masculine, rough, or wild characters such as Revy in Black Lagoon. She has also played many iconic and long-running roles, including Winry Rockbell in the first Fullmetal Alchemist anime, Miriallia Haw in Mobile Suit Gundam SEED and its sequel, Sei Sato in Maria-sama ga Miteru, and Ellen Kurokawa / Cure Beat in Suite Precure. In the Persona 3 film series, she reprised her video game role as Yukari Takeba. More recently, her roles have included Ghislaine Dedoldia in Mushoku Tensei: Jobless Reincarnation, the Great Sage and later Raphael in That Time I Got Reincarnated as a Slime, and Hana Tōjō in the Uma Musume Pretty Derby franchise.

In addition to anime, Toyoguchi has an extensive career in video games. She is well-known for voicing Junko Enoshima in the Danganronpa series, Paine in Final Fantasy X-2, Rosie in Valkyria Chronicles, and Aqua in the Kingdom Hearts series. She also provided the Japanese dub voice for Pyrrha Nikos in RWBY: Ice Queendom.

Throughout her career, Toyoguchi has formed lasting professional relationships with other voice actors. She is close friends with and a member of the theater group "R*L" alongside Kazusa Murai and Fumiko Orikasa, and another group with Rie Kugimiya and manga artist Mihona Fujii. She is also admired by voice actress Mamiko Noto, who calls her "onee-sama" (big sister), a relationship that began when they played sisters in Maria-sama ga Miteru.