Ahad is a Middle Eastern given forename primarily used by Muslims (e.g. Ahad rezayan) and Jews (e.g. Ahad Ha'am). It is also used as a family name (surname) (e.g. Oli Ahad).
In Arabic Ahad means "one", "unique" or "matchless" and is usually used by Muslims when referring to God by prefixing Ahad with Al-, i.e. Al-Ahad.