Peter Parker met her in college where his preoccupied life as Spider-Man made him seem aloof. Eventually, Gwen warmed up to him and a romance developed. That became more complicated when her father, Police Captain George Stacy, was killed by falling debris from a battle which involved Spider-Man and Doctor Octopus. Gwen blamed Spider-Man for that event and so it hung over their relationship like a Sword of Damocles. But unlike the earlier situation with Betty Brant, Peter was ready to deal with it.
Eventually, Gwen Stacy was held on George Washington Bridge by the Green Goblin. When the Green Goblin pushed her off, Spider-Man grabbed her legs with a string of web, but the sudden stop broke her neck. A clone of her was developed by an insane professor, but eventually that woman established her own identity.
In the Spider-Man movie of 2002, Mary Jane Watson was held at the bridge instead of Gwen Stacy, who is not in the movie. Spider-Man manages to save both Mary Jane and a group of children trapped in a cable car. Spiderman then kills the Green Goblin before he gets another chance to kill MJ.
Stacy is also ignored by other comic adaptions.