congregator (plural congregators)
1.A person who congregates or assembles
Congregators have to be up there in the top ten most annoying public transit users.
They all congregate at the front of the bus, so the back of the bus remains empty. There is nothing more annoying than waiting for the bus and have it drive right by you with no one in the back.
Out of consideration for other public transit users, move to the back of the bus so others can get on. You are not the only one who needs to get somewhere. May you have bad bus karma if you do this.