The Javelin is a spaceship employed by the Justice League. As an aircraft, the Javelin was capable of vertical takeoff and landing. There were six Javelins that were constructed and used by the League.
In DCAU, the Javelin was the main vehicle used by the Justice League. In Justice League Unlimited, the reorganized Justice League made use of a large fleet of Javelins, based in hangar facilities on the second Watchtower.