Lepidodactylus lugubris or Hemidactylus garnotii. Both reproduce by parthenogenesis and either will quickly outbreed their enclosure.
In June of this year, as an experiment, I housed 2 adults in a 12x12x18 zoo-med tank. As of now, I have 7 geckos of varying ages, and 8 eggs. I don't think my experiment will be able to run to next June as I had planned, as it's getting cramped for space.