One of the founders of rhode island, who was banished from the massachusetts bay colony, and convicted in a trial was

The correct answer is Roger Williams.

Roger Williams was banished from the Massachusetts bay colony due to his "new and dangerous ideas." Williams was a huge advocate of religious freedom, separation of church and state, getting rid of slavery, and dealing with Native Americans in a kind manner. All of these characteristics made him an outcast in the extremely religious Massachusetts bay colony, leading to his exile.