Who discover aluminum?

I don't think it was particularly discovered. Scientists had suspected something unknown in alum as early as 1787. Hans Christian Oersted was the first to produce tiny amounts of it.

Humphry Davy in 1808 identified the existense of a metal base of alum, which he at first termed alumium and later aluminum.
Some credit Oersted, a Danish chemist, other credit Wohler, a German