R51

R51 may refer to:
 * R51 (South Africa), a road
 * HMS Chevron (R51), a destroyer of the Royal Navy
 * HMS Perseus (R51), an aircraft carrier of the Royal Navy
 * Nissan Pathfinder (R51), a sport utility vehicle
 * R51: Toxic to aquatic organisms, a risk phrase
 * Remington R51, a semi-automatic pistol