Gloydius is a genus of pit vipers endemic to Asia, also known as Asian moccasins or Asian ground pit vipers.

[3] Species of Gloydius are found in Russia, east of the Ural Mountains through Siberia, Iran, Himalayas from Pakistan, India, Nepal, China, Korea, Japan and the Ryukyu Islands.

In the above list, a taxon author in parentheses indicates that the species was originally described in a different genus.

Due to the strong morphological similarity, these snakes were classified in the genus Agkistrodon until very recently.

However, by 1999 cladistic studies clearly showed that Agkistrodon did not form a clade (indeed, it was not even paraphyletic) and was thus split into several genera.