Evelyn is a female fish citizen of  Bikini Bottom who mostly appears as a background character. She is usually seen in the Krusty Krab or Goo Lagoon.
She is dark pink with a light orange dorsal fin and has light orange and dark pink arms. She has light yellow eyes with black pupils, and has orange lips. She wears a red skirt, red bra, and black shoes.
Her first appearance is in the episode "
Ripped Pants." Her name is revealed in " Band Geeks," where she is a member of Squidward's band. She has attended many Bikini Bottom special events, including the cook-off between SpongeBob and King Neptune, " The Fry Cook Games," " The Great Snail Race," and Squidward' clarinet recital. She also was attended such as seen in " Slimy Dancing" and " Suction Cup Symphony."
She appears blue in "
No Nose Knows." She tells Squidward that she needs a refund for a Krabby Patty in the episode " Have You Seen This Snail?" In " Once Bitten," it is revealed that she is married to Harold "Bill" Reginald. It is also revealed in " SquidBob TentaclePants" when she marries Harold, she says "I'm scared!"
She repeatedly switched between having and not having sunglasses which are identical to the ones SpongeBob and Sandy wear to act like Jelliens in the episode " Planet of the Jellyfish."
She was accidentally given a belly button in at least one scene from " Nautical Novice."
Her appearance is similar to Annette.
In " Good Ol' Whatshisname," she calls Squidward "Mr. Grouchy Squidguy."