The Guardians (originally "The Granite State Guardians") are a team of heroes in the Marvel Universe. They banded together following the "Onslaught" storyline in the mainstream Marvel Universe, around Thunderbolts #1, where many of the major Marvel heroes (the Fantastic Four and the Avengers) were believed dead. In the Guardian universe, the return of the heroes (after the events in Marvel's "Heroes Reborn" series) turned out to be the work of Franklin Richards' powers; thus the Avengers and the Fantastic Four are still gone, and may never return.
The team is currently based out of a skyscraper headquarters in Boston, but they travel all over the New England area and the world, handling various menaces. The team is supported by a coalition of New England states and touted as the area's "hometown heroes." The team's roster is:
I've run a lot of super hero RPGs in my time, but I've got to say the Marvel Super Heroes Adventure Game really captures the essence and feel of the comics for me. The rules are simple and open-ended and the card system allows players greater control over their character's actions and successes. I also love the "Doom Pool" mechanic for villains. If you are into super hero RPGs, you owe it to yourself to check it out.