Marianne

Marianne, also known as Miss Goldenweek (Miss April Fools Day in 4Kids' English dub) partnered with Mr. 3, a wax sculptor. She hates work, is a talented painter, and can be seen constantly eating her favorite snack: rice crackers. She also appears younger than the other Baroque Works agents. She wields Color Traps, which control a person's emotions or affect their fighting abilities by painting colors upon their body. Miss Goldenweek uses these Color Traps to control Luffy, attempting to prevent him from defeating Mr. 3.

[Spoiler] She is defeated by Karoo, but appears in a cover series in which she masterminds the rescue of the captured Baroque Works agents. [/Spoiler]

[Spoiler] In the same cover series, by painting a rainbow swirl in the sky through the use of her powers she transformed all of the fugitive agents of Baroque Works into their dreams. This action revealed that she wanted to become a true artist, complete with a beret and a mustache. [/Spoiler]

(Source: One Piece Wikia)