Try this fun experiment:
1) Make a Line or XY chart using the conventional markers
2) Insert a picture (or piece of clip art) onto the worksheet and resize it
to about 1/8 "
3) Select and copy the photo, click on the data series in the chart and use
CTRL+V to paste.
All the markers have been replaced by the picture

When you ask about using Letters one wonders if you would be better with
data labels.

best wishes
--
Bernard V Liengme
Microsoft Excel MVP
http://people.stfx.ca/bliengme
remove caps from email

"KBICarl" wrote in message
news
Is there a way to expand the Custom Data Merker selection list to include
additional symbols and (hopefully) letters?