Created By Column


I have a sheet that uses the created by system column which works and brings over the email addresses of the users that are creating the row, however is there any way for me to only bring over the last name of the user? I don't need the whole email address because having it as the whole email address makes the graphs in the dashboard associated with this sheet very bulky. Also there is no way to have the created by column line up with the bar in a bar graph in dashboard?