General terms:
* Community: A group of people living in the same place or having a particular characteristic in common.
* Society: A group of people living together in a more or less ordered community.
* Association: A group of people who have joined together for a common purpose.
* Organization: A group of people working together in a structured way to achieve a common goal.
* Collective: A group of people who share a common interest or goal.
More specific terms:
* Movement: A group of people working together to bring about social or political change.
* Lobby: A group of people who try to influence government policy.
* Faction: A group of people within a larger organization who have different views or interests.
* Coalition: A temporary alliance of different groups who have come together to achieve a common goal.
* Network: A group of people who are connected through shared interests or goals.
The best word to use will depend on the specific context of the group. For example, if you are talking about a group of people who are working together to protect the environment, you might call them an environmental movement. If you are talking about a group of people who are trying to influence government policy on healthcare, you might call them a healthcare lobby.
Ultimately, the choice of word is up to you, but these options should give you a good starting point.