Rosie, in Rosie and the dance of the dinosaurs - a children's book about a child with nine fingers
Sauron, from The Lord of the Rings book, during the time he took physical form, who had his ring finger cut off by Isildur.
Tim, from Eric Bogosian's play, Suburbia, and the movie of the same name, cut off one finger in order to be discharged from the US Air Force.
The narrator in A Prayer for Owen Meany, by John Irving had his right index finger cut off by his best friend in an effort to prevent the narrator from being drafted during the Vietnam War.