was Darth Sideous' assassin. He may not have showcased a lot of political flair, but he wasn't the inquisitor that was manipulating the Republic, Sideous was. And he was certainly sneaky enough, he tracked Qui-Gon and Obi-Wan to Tattooine and ambushed them at their ship.
Though well trained in the ways of the Sith, Maul was technically a Sith Lord in violation of the Rule of Two because his own Master was at the time apprenticed to another, the Muun Sith Lord Darth Plagueis. However, he was kept as a Sith Assassin and thus technically wasn't an actual Sith apprentice, and in addition, Plagueis had discontinued the Rule of Two by the time he trained Sidious.