Door

A door god is a Chinese decoration placed on each side of an entry to a temple, home, business, etc., believed to keep evil spirits from entering.

"The custom dates back to the Tang Dynasty, whose founder Emperor Tang Taizong (599 - May 26, 649) honoured two of his most loyal generals - Qin Qiong and Yuchi Jingde - by having their painted portraits hung on his front door. Ordinary families soon adopted the imperial custom, putting woodblock prints of the ever-vigilant generals on their front gates in the hope of attracting good luck and fending off evil spirits. The Door God business soon spread throughout China, adding other folklore heroes and mythological figures to the repertoire."

From Wiki
http://en.wikipedia.org/wiki/Door_god