How much is Nelly Dean to blame for what happens in Wuthering Heights? Is she the villain of the story?Specific examples would be appreciated.

Nelly Dean is the primary narrator in "Wuthering Heights."

She is NOT the villain of the novel.

Although she is the primary narrator, she is also a character who takes part in the action in the novel.

1. In Ch.4 Nelly tells us how she joined Hindley in hating Heathcliff: "and to say the truth I did the same."

2. In Ch.9 Cathy confesses to Nelly that she is in love with Heathcliff and Linton  at the same time. Nelly refuses to promise to keep this a secret. This is why she reveals this to the secondary narrator  Lockwood and so we the readers are able to understand Cathy's complex relationship with  both Linton and Heathcliff.

3. Ch.12 clearly reveals the dilemma  Nelly finds herself in. Cathy and Linton quarrel and Cathy locks herself up in her room while Linton ignores her and immerses himself in his books. Cathy becomes dangerously ill but Nelly thinks that nothing is seriously wrong with her and does not inform Linton. When Linton comes to know of Cathy's precarious  state of health he becomes angry and scolds Nellly to which she replies "I performed the duty of a faithful servant in telling you, and I have got a faithful servant's wages."

4. In Ch24. younger Cathy tels Nelly Dean how she made fun of Hareton Earnshaw's illiteracy. At once Nelly Dean checks her by saying that Hareton is her cousin and that she should not make fun of him, thus sowing the seeds of love between Younger Cathy and Hareton.