The Legend of Zelda: Compass and Boomerang

 I'd call these items from the original Legend of Zelda game indispensable, but they're actually two items you don't need to pick up to beat the game. They are without a doubt iconic, with some form carrying forward to almost every Zelda series game afterward.

 (Spoiler: This boomerang made of LEGOs did not come back when thrown. Real boomerangs aren't great at that either, so I don't feel bad about it.)