Mobilizer (noun)

1. A person who organizes and motivates others to take action.
2. A person responsible for organizing and activating a group, organization, or movement.

Origin:

From the word "mobilize" meaning to organize and make ready for active service.

Examples:

1. She was a great mobilizer and she was able to get many people to join the cause.
2. He was the main mobilizer in the student movement.
3. The mobilizer worked to bring the community together for the event.
4. She was appointed as the mobilizer for the political campaign.
5. The mobilizer was able to mobilize thousands of people for the march.