One way:

Create a list with A to Z in A1:A26. Select the cells. Choose
Tools/Options/Custom lists. Click Import.

This will only give you 26 cells without repetition. You could make a 52
item list from A to AZ, etc.



In article ,
Janus wrote:

I can easily create a column of numbers that increase in increments of 1
in each successive cell by adding 1 to the cell above. The first cell
is the only cell where I manually input a number. I want to set a
column so that I can input a letter, say E, in the top cell and the
cells below will fill in with F, G, H, etc. If this can be done, am I
limited to a maximum of 26 cells to match the number of letters in the
alphabet, or can I go into letters like AA, AB, AC, etc.