Owls are not bad luck; they are simply birds of prey of the order Strigiformes. However, some cultures around the world consider owls to be bad omens. On the other hand, other cultures consider them to be favorable. The bird of the goddess Minerva was an owl, for example.
One place where the owl is considered bad luck is Arabia. The owl represents evil spirits who steal children in the middle of the night, and the death owl perches over the grave of a murdered man and hoots until his murder is avenged.
One of the evil gods of the Aztec culture wore a screech owl on his head, and in Cameroon, the owl is so feared that it is not named. The owl was a symbol of the underworld for the Celts and of the god of darkness for the Etruscans. In Germany, it's bad luck for an owl to hoot during the birth of a child.
The owl is also a sign of bad luck in Jamaica and Iran, and it is forbidden to eat one in the Muslim religion. The owl was an unclean bird for the Hebrews. The Ainu people of Japan believe that the horned and barn owl are evil, though the eagle owl is revered.