Door gods guard the entrances of temples, homes and other buildings. They are represented in the form of statues or paintings.
Legend has it that these gods became a tradition thanks to two Tang Dynasty generals who were tasked to guard the entrance to the Emperor Tai Zong’s (太 宗 皇 帝) bedchamber as the ruler suffered from nightmares and feared that demons and ghosts would come to abduct him. The emperor slept soundly when the generals stood guard. Even portraits of the two warriors were said to be sufficient in ensuring that Tai Zong got a good night’s rest.
The two generals were Yuchi Gong and Qin Shu-bao, and they are the ones usually painted on the main doors of temples and so forth. Yuchi Gong (also known as Yuchi Rong, Jingde and Duke Zhongwu of E) is easily indentifiable as the door god with swarthy skin.
Yuchi Gong 
Qin Shubao
These paintings of Yuchi Gong and Qin Shubao can be seen at the Thean Hou or Tianhou (天后) Temple in Seputeh, Kuala Lumpur, Malaysia.
The following door gods include Yuchi Gong (dark skinned), but I can’t identify the others. They are at the Tow Moo Keong Temple on Gat Lebuh Noordin, George Town, Penang. (Tow Moo or Dup Mu Yuan is the Queen of Heaven, mother of the Nine Emperor Gods.)
Three Stars 