The tree kingfishers, also called wood kingfishers or Halcyoninae, are the most numerous of the three subfamilies of birds in the kingfisher family, with around 70 species divided into 12 genera, including several species of kookaburras. The subfamily appears to have arisen in Indochina and Maritime Southeast Asia and then spread to many areas around the world. Tree kingfishers are widespread through Asia and Australasia, but also appear in Africa and the islands of the Pacific and Indian Oceans, using a range of habitats from tropical rainforest to open woodlands.

Kingfishers are a family, the Alcedinidae, of small to medium-sized, brightly coloured birds in the order Coraciiformes. They have a cosmopolitan distribution, with most species living in the tropical regions of Africa, Asia, and Oceania, but also can be seen in Europe. They can be found in deep forests near calm ponds and small rivers. The family contains 116 species and is divided into three subfamilies and 19 genera. All kingfishers have large heads, long, sharp, pointed bills, short legs, and stubby tails. Most species have bright plumage with only small differences between the sexes. Most species are tropical in distribution, and a slight majority are found only in forests.