Spike aka
William the Bloody
Spike first appears in "School Hard" (2.3), when he drives his car into the 'Welcome to Sunnydale' sign on the outskirts of town. His first words as he reaches the Hellmouth - "Home sweet home" - are apparently a reference only to the idea that the Hellmouth is, de facto, home to all vampires, rather than any implication that he has ever been to Sunnydale before. As the episode continues, the Anointed One holds court, and his followers argue over who will take the place of the Master, as Spike arrives there.

He brags that he has killed two Slayers, and then Drusilla enters. They are obviously a couple, though Drusilla seems sickly and insane. Spike's world revolves around caring for her, as well as his thirst for power - he vows to kill the Slayer.

Later that night, Spike goes to the Bronze with another vampire to look for Buffy. Spike's companion, 'Big Ugly', draws Buffy into combat as Spike watches. Despite his bragging, 'Big Ugly' is no match for the Slayer, and is easily dispatched. Afterwards, as the Scoobies discuss Spike's arrival, and Angel reveals that he knows him. Later, Giles finds references to Spike in the Watcher Diaries. 

On Parent-Teacher Night, Spike and his hordes attack Sunnydale High, but are defeated, Spike himself being clobbered by Joyce. He is angered by this, and to save a telling-off from the Anointed One when he returns to the Master's former lair, he kills him. Spike next appears in "Halloween" (2.6). It is revealed that he has been taping Buffy in combat, in order to attempt to discover any weaknesses she may have. Yet again, he tries to attack Buffy, but yet again he is foiled.

In the next episode, "Lie To Me", he has another shot at the Slayer, but Buffy manages to fend him off by threatening Drusilla. Also in this episode, Spike shows his jealousy of Angel, due to his former involvement with Drusilla. In the two-parter "What's My Line?" (2.11 & 2.12), Spike has finally managed to restore Drusilla to health, only to become an invalid himself. Incapacitated in a wheelchair, he becomes somewhat depressed. Even when he helps the love of his life to assemble the Judge in "Surprise" (2.13), he seems to be playing along for Dru's benefit.

However, as Buffy and Angel make love on Buffy's seventeenth birthday at the end of "Surprise", causing Angel to lose his soul and revert to his demonic persona, the fire in Spike begins to burn once more. Angelus stays with Spike and Dru, and Spike's jealousy continues to eat at him.  In fact, this does Spike some good as it gives him the inspiration to get up out of his wheelchair at the end of "I Only Have Eyes For You" (2.19) and go and raise merry hell somewhere.

In the series finale two-parter, "Becoming" (2.21 &  2.22), Spike realises that Angelus's plan to destroy the world won't be good for the vampire race, and the only thing that matters to him is that he gets Drusilla back.  To do this, he forms an unlikely alliance with the Slayer, and vows to Buffy that he will betray  the others if she lets Drusilla live, and the two of them will leave Sunnydale for good.

Only 120 years old (using the most recent evidence, "Fool For Love"), Spike has already killed two Slayers. He's tried multiple times to kill Buffy, but to no avail (but then again, she hasn't killed him either). After being gone for all but one episode of season three ("Lovers Walk"), Spike became a regular in season four, and he's not having any better luck in Sunnydale this time around — thanks to the Initiative, he's got a chip in his head which renders him unable to kill or hurt anything other than another demon (which he does, leaving him unpopular in the demon world). Much to his chagrin, he's not only impotent, but also dealing with a major crush on the Slayer herself.

Spike is played by James Marsters.