The Savior

''The heroes of The Hero. Who's saving whose hide now?''

Like what the slidetext said, the Cavalry is the person or people that rescue(s) the Hero and their friends when they're needed. They may be counted or responsible for many Ex Machina moments due to how they can seemingly show up out of nowhere with the greatest timing. It might not be the Cavalry's job to save people; they might just be obliged to do it because the ones they're saving can't defend themselves.