Hero

Hero commonly refers to Agent 3, Agent 4, or Agent 8, the protagonists respectively in and  single-player modes, Octo Valley,  Octo Canyon, and the Octo Expansion. It may also refer to Octo Valley or Octo Canyon itself, also known as Hero Mode.

Or the suits worn by Cap'n Cuttlefish's agents.
 * Hero Suit
 * Armor

Or the Replica gear based off these suits.

Or the main weapons used in Octo Valley and Octo Canyon.
 * Hero Shot
 * Hero Charger
 * Hero Roller
 * Hero Blaster
 * Hero Brella
 * Herobrush
 * Hero Dualies
 * Hero Slosher
 * Hero Splatling

Or the Replica weapons based off of them.

Or the Splatfest.
 * Hero vs. Villain