Basemath

There are two or three women called Basemath (or Basemeth according to some translations) in the Bible:

The first Basemath is a wife of Esau and daughter of Elon the Hittite (Genesis 26, 34). In Genesis 36, 2 Esau marries Adah, daughter of Elon the Hittite. This means that Adah is either a sister of Basemath the First, or the same woman with two names.
The latter is likely, because in Genesis 36, 3 Esau marries Basemath the Second, who is the daughter of Ishmael and sister of Nebaioth. A few chapters earlier, in Genesis 28, 9 Esau marries Mahalath, who is also a daughter of Ishmael, and a sister of Nebaioth. So Mahalath could be a sister of Basemath the Second, but it could also be the same woman with two names.
Finally, there is Basemath, a daughter of Solomon who married Ahimaaz (1Kings 4, 15).