The Gold Key is an ordinary looking, golden key in Star Fox Adventures. It is the very first collectable item in the game and is essentially used to introduce the concept of items.
It is found by Krystal in the SharpClaw Galleon, shortly before running into General Scales. It is later used to open up an old-looking locked door in Krazoa Palace. The room is very small, and only contains a Fuel Barrel. By this door, the game also instructs how to use the C-inventory.