My given name was "Diana Bennett" and man if you google that name you'll get.... an awful lot of people who aren't me. It's pretty unremarkable!
In highschool I had an art teacher who mentioned that she wasn't opposed to taking her husband's name, but her whole reputation as an artist was tied to her maiden name by the time she got married, so she kept it. I thought that if I ever got married I'd like to be able to have the choice, so that's when I decided I was going to need a pen name, so that no matter what my last name was, people would recognise me. I chose "Shazzbaa." (There's a story behind it.)
It's what I used online, and then I introduced myself as Shazz or Shazzbaa almost exclusively in college, to the point that when I graduated and my name was called, lots of classmates were shocked to learn Shazzbaa wasn't my legal name. My friends and family mostly know me as Shazz, there's just a few grandparents and such who never switched over. My given name feels like a weird baby name I've outgrown.
So I guess I use a nom de plume, technically; but if you ask about my real name, Diana is my legal name, but Shazzbaa is my real name.