Spirits/Invisible People/Posession

The pack

Interrupting a ritual, Xander and four other SHS students are possessed by hyena spirits. They become ruled by their animal instincts, traumatizing and attacking their fellow students, and even eating Principal Flutie.

Out of sight, out of mind

Constantly ignored by her classmates, Marcie Ross becomes as they perceive her: invisible. She hangs around the hallways of the school, attacking the popular kids, especially Cordelia.

I only have eyes for you

As the Sadie Hawkins Dance approaches, strange things start to happen at SHS. The gang figures that two spirits unable to find rest are reliving their tragic deaths. The end up possesing Buffy and Angel, allowing them to end the conflict between them and rest in peace.

Pangs

A group of construction workers unravel a buried catholic mission that was in charge of the local Native Americans. A spirit, seeking revenge over the white men starts attacking people in Sunnydale as Thanksgiving approaches.

Fear, Itself

Trapped in a house on the night of Halloween, everyone's fears become true and Xander becomes invisible.

Where the wild things are

When the Iniatiave soldier/Frat Boys throw a party at their house and sex-crazy Buffy & Riley get it on, the crowd freaks out as a group of frustrated teen spirits take over the house.

Same Time, Same Place

Fearing the reunion with her friends after her evil freak-out, Willow becomes invisible to the gang and the gang invisible to Willow.