Who is the comics character Querl Dox?

Querl Dox is the "real name" of the character Brainiac 5 of the "Legion of Super-Heroes."

The Legion (LSH) is a group of young DC Comics superheroes, set in the 30th and 31st century. They appeared as peers of the young Superman character "Superboy" in various DC Comics (Adventure Comics, Action Comics, Superboy and the Legion of Super-Heroes, The Legion) and in a DC animated series (2006-2008).