Anansi the Spider is one of the lesser gods from the Ashanti (West African) mythology. Anansi features mostly in their folktales. The Anansi stories came with the Africans to the Caribbean and to the United States.
The main god in this mythology is Nyame, the omnipotent and omniscient sky god. Nyame's wife is Asase Ya, the earth goddess of fertility. In some stories, Anansi is the son of Nyame and Asase Ya. In others, he is simply one of the lesser gods. Anansi is usually depicted has having a wife (alternately clever and terribly gullible) and one or more children.
Anansi is a trickster. The library is teeming with Anansi tales for children. Because he's such a mischief maker, his stories are often funny and entertaining to children.
However, many of the Anansi tales are not suitable for children. They can have violence, sex and other themes inappropriate for younger readers.
One of the things I like best about the Anansi stories, and Gaiman states this best, is "The stories are all Anansi's, but he doesn't always come out ahead." (Anansi Boys, page 160.)
Some of the other well known trickster gods are Coyote, Loki, and Raven, from other mythologies.