What are some novels that depict loneliness, social isolation and alienation in the main character?

[Cattleman]

I agree that "Catcher in the Rye" and "Of Human Bondage" definitely fall into this category, I would also suggest "The Handmaid's Tale" by Margaret Atwood. While the main theme is about social dysfunction, you cannot ignore the narrator/protagonist's feelings of isolation, depression, etc.

[AnneAustin7854]

I try not to read anything too sad and depressing but when someone mentioned Cormac McCarthy I remembered 'The Road'. Although the father is with his son, it is about two people facing up to a new, frightening world alone. It's a fantastic book with a heartbreaking ending.

[Jefferson22478]

The Painted room by Lounis Tiar. the story is set in a room in isolation

[Cattleman]

One which just came to mind is, believe it or not, Mary Shelly's "Frankenstein." Several chapters are from the "Monster's" (though I don't like to call him that) point of view, and show his feelings of isolation, loneliness, etc.

[Desertsage9]

A novel by John Barth, "The End of the Road", is about alienation. It's one of his early novels, and it depicts a man who finds the everyday trappings of life to be shallow and uninspiring. It's been a long time since I read it, but I remember it's worth reading as precursor to Barth's later work where he seems to find answers to the alienation in humor, games, and absurd/funny views.