Elizabeth "Bess" Marvin is a character in the Nancy Drew Mystery Stories series. She is one of Nancy Drew's best friends, along with George Fayne, who is Bess' cousin. Bess and George are introduced to readers in The Secret at Shadow Ranch. Bess is described as blond, slightly plump, pretty, and blue eyed. She is very feminine, and is easily frightened when involved in Nancy's adventures. Bess always fears the worst is going to happen and insists that Nancy gives up several mysteries. She is somewhat flighty, fickle, and a bit of a flirt - quite the opposite of cousin George, who is more practical, steady, and very much a tomboy.
Bess loves to shop, and has a weakness for food, especially chocolate and ice cream. In most volumes in the series, George makes at least one comment on Bess' diet. Bess, admittedly, cannot stick to a diet, no matter how she tries.
Her boyfriend is Emerson College student Dave Evans. She is introduced to him in Nancy's Mysterious Letter. Bess is a true romantic. She is loyal, and she always enjoys helping Nancy, albeit with some trepidation. Although George considers her a coward, Bess does sometimes surprise even herself with her bravery, and she occasionally deciphers clues that stump even Nancy.
In the Nancy Drew movie of 2007, Bess was played by Amy Bruckner.
In the television series The Hardy Boys/Nancy Drew Mysteries (1977-1979), Bess was played by Ruth Cox.