Badumna is a genus of intertidal spiders that was first described by Tamerlan Thorell in 1890. They are harmless spiders that can be found around human structures and buildings. They are darkly colored, usually with a lighter colored pattern on the abdomen. The most well-known species is B. insignis, also known as the "black house spider" or "black window spider". Most of the species are from Australasia, but some have been introduced elsewhere. B. longinqua is the only species introduced to North America, now found in urban areas along California's Pacific coast.