I'm not planning on using a pen name. In fact, I plan on doing my best to defy the publishing industry and use my plain old name for everything I write, in every genre.
But. In the case of needing a pen name, such as competitions where they require one, I have one at the ready.
George for George Eliot. Also for George Tate, my humanities professor from my Freshman year in college who my roommates all said I was like, and then when we were analyzing ourselves and coming up with boy names for each of us, because that's what college girls do, my boy name was George.
Lewis for the very obvious reason of C. S. Lewis.
So there is my carefully planned pen name that I have in my back pocket in case of emergencies.