Marco Pelaez is the actor who plays Marco the Pharmacist is Season 1 and Season 3. He has appeared in three episodes of Season 1: Occam's Razor, Detox and Love Hurts and three episodes of Season 3: Whac-A-Mole, Merry Little Christmas and One Day, One Room.
His only other television work other than on House M.D. was as a news reporter in the 2004 film Martha.