Sidekicks

Main characters that typically work alongside main protagonists (or antagonists in some cases). For the case of heroic sidekicks, they almost always help the main heroes save the day (or in a few cases save the day on their own, whenever the main heroes are incapacitated in some form or another like being imprisoned or sick); for the case of villainous sidekicks, they almost always help the main villains commit their crimes & misdeeds and are regarded to be of a higher rank (even being called right hands of their bosses) than mere minions. There are even a few cases where certain villainous sidekicks eventually change sides to become good doers.