Half-door

Half-doors are redstone items that resemble trapdoors standing upright. Only Leprechauns and dogs and cats can open these. The player can, but cannot be walked through.

Appearance
It looks like a trapdoor standing vertically.

Uses
Dogs, cats, and leprechauns can open these doors. It could make a good pet door for your animal to escape from monsters. Some zombies will attempt at breaking down half-doors, as they only break down doors closest to them. Zombies are incapable of doing so, so it will even offer protection for your house in ways.

Crafting
It can be crafted by the same way as a trapdoor, but you replace the top middle wood plank with redstone. This will result in a half-door.