Using the fill handle is easy. Simply start typing a list of consecutive numbers, dates, etc. and drag the rest. You can easily fill 100 cells in no time at all. Well what if you wanted to fill the alphabet down a list of cells? Unfortunately, Excel doesn’t have this functionality built in. If you were to start typing the alphabet down column A, so that A1=A, A2=B, A3=C, and then drag the rest, you would only get A, B, C repeated as far as you dragged the fill handle.
There are two ways of making this work. The first is through a formula, and the second is by using a custom list.
To get the alphabet with a formula, type the number 65 in cell A1, and drag down to cell A26. Now column A should have the numbers 65 through 90. In cell B1, type =CHAR(A1), and drag this down to cell B26. Column B should have the capital letters A through Z. If you want lowercase, simply start with 97 and fill to 122 in column A.
Alternatively, you could manually type your list A through Z in cells A1:A26, then select that range (A1:A26). Click Tools | Options | Custom Lists (or in Excel 2007 Office Button | Excel Options | Popular | Custom Lists). On the bottom of the menu, click Import, where it says $A$1:$A$26. You’ll see A through Z appear under custom lists. Now whenever you type A, then drag down it will fill through the letter Z then loop back to A and start all over again as far as you drag.