Depressed characters in literature

In Charles Dickens's "David Copperfield", an elderly widow Mrs. Gummidge, lives with the Peggotys (friends of David), constantly mourning for her husband & saying "I am a lone, lorn creature & everything goes contrary with me", which is her catch phrase. However after "Little" Emily's elopement, she becomes active & helps the family.

In "Alice in Wonderland", Alice meets a Mock Turtle, who is perpetually lachrymose, possibly because it's destiny is to end up as Turtle Soup. It's companion is the Gryphon, with which, it dances "a lobster quadrille".

Eeyore, the grey donkey in "Winnie the Pooh", another chronically depressed character, is always wallowing in self-pity. It feels the other animals in Hundred Acre Wood neglect it & even ill-treat it, probably with good reason, because when it falls into a stream (likely "bounced" into it by Tigger), to rescue it, the others drop a stone right on top of it, which it adroitly avoids.