Give this a try (tested it quickly & will work only on single characters).
Enter it as an array formula, meaning enter it by pressing Ctrl-Shift-Enter

=CHAR(MAX(CODE(A1:A4)))


"Modus" wrote:

Is there a way of returning the largest letter in a series of cells with
letters in it for example Cell 1 = A, Cell 2 = B, Cell 3 = C, Cell 4 = D the
formula would return 'D'

Please help