Both a girl's and boy's name used in English. Its source is
aesc leah, an Old English phrase meaning "Ash grove." Nicknames include
Ash and
Lee. Seriously.
It began as a surname, but grew in popularity as a personal name due to the character Ashley Wilkes in Margaret Mitchell's 1936 novel Gone With the Wind. After a long reign of being dominated by female usage, Ash began to grow in popularity again from Sam Raimi's Evil Dead trilogy. One can only wonder how the name will fare after Ash of Pokemon...