Tom,
your question is a bit confusing. I assume that you mean the last
filled cell in the column and not the cell which was last entered
chronologically (which is much more complex and requires VBA)

=INDEX(H2:H65536, MAX(ROW(2:65536)*--(H2:H65536<"")),0)

It is an array formula, therefore it should be entered with
Shift+Ctrl+Enter.

HTH
Kostis Vezerides