protagonist /prə- or prō-tagˈə-nist/

1. Orig the chief actor, character or combatant
2. Now often applied to any (or in pl, all) of the main personages or participants in a story or event
3. (loosely) a champion or advocate

• one-sidedness
• onesie
• onesies
• one's last resting place
• one's native heath
• one's other half
• one's own
• one's own flesh and blood
• one's own man
• one's own woman
• one's self
• one-step
• one-stepped
• one-stepping
• one-steps
• one-stop
• one's true colours
• one-time
• one-to-one
• one-track
• one-trick pony
• one-two
• one-twos
• one-upmanship
• on every hand