The key is the top left key under escape, on non-US keyboards. Other keyboard layouts will differ, but the key is usually to the left of 1, and just under the Escape key ( Esc). The grave accent key shifts to tilde ( ~) on US keyboards, and the not symbol ( ¬) on UK keyboards. To access the console, use the grave accent key ( `) while in-game (Unpaused).
10 Reputations ( Fallout: New Vegas only).