P Warp Door
P Doors are Warp Doors that can only be entered when a P Switch is active. These Warp Doors made their first appearance in Super Mario World in the Donut Secret House.
History
Super Mario series
Super Mario World
In Super Mario World, P Doors appeared in the levels Donut Secret House, Vanilla Ghost House and Forest Ghost House. They had the same sprite as a Warp Door, but with a light blue palette.
Super Mario Maker
In Super Mario Maker, P Doors were introduced in the version 1.30 update. They were given new sprites for all styles, in the same blue as the P Switches with a white or blue "P". Unlike in Super Mario World, they are visible as outlines when not active.
Gallery
Super Mario Maker (Super Mario Bros. style)
Super Mario Maker (Super Mario Bros. 3 style)
Super Mario Maker (Super Mario World style)
Super Mario Maker (New Super Mario Bros. U style)