In the wake of the crazy astronaut story, WaPo lists famous stalkers. They left out Lady Caroline Lamb, who was kind of the prototype for celebrity stalkers.
Lady Caroline had a tempestuous affair (Is there any other kind?) with Lord Byron and refused to take no for an answer when the poet broke it off. She showed up at his place dressed like a boy; she sent him a lock of her pubic hair; and she wrote a roman a clef about the affair. For a little light relief, she'd threaten to stab herself, or him, and generally made a public nuisance of herself.
Lady Caroline Lamb was the one who characterized Byron as "mad, bad, and dangerous to know." I believe the feeling was mutual.