- Minga in Chill Out, Scooby-Doo!
- Kung Fu Maiden, Nikki Starlight, Maggie Xi and a fire-breathing groupie in Scooby-Doo! Unmasked
Guest landed her first acting role at the age of 4, as a talking mouse in a school play. She has done voice work in five separate animated productions with fellow voice actor Kirk Bailey.
Upon winning the role of Mei Ling in Metal Gear Solid, Guest picked up her character's Chinese accent over the course of three days. During the making of Metal Gear Solid, Guest was the second choice for the role of Mei Ling because the producers balked at hiring Guest, who at the time was an inexperienced voice actress, to voice such a fairly important role. However, the woman originally favored for the role botched her final audition so badly that Guest ended up getting the role, which is arguably her most famous one to date.
From 1997 to 1999, Guest was unable to go by her real name when credited due to Screen Actors Guild stipulations, which led to her using the pseudonym Kim Nguyen when the credits rolled.