A vigilante might be applicable depending on how their methods of going about bettering the world--for example, killing other people despite otherwise good intentions. There is no minimum "criminality", but we strongly encourage people to think about who they're apping and how they might apply to the setting. For example, someone who just littered probably isn't going to be as applicable to the plot as someone who actively stole or murdered someone, unless the person is somehow overwhelmed with guilt for littering. (Think Chidi Anagonye from The Good Place.)