From south-west Dominican Republic
The Jaragua Sphaero or Dwarf Gecko (Sphaerodactylus ariasae) reaches 16 to 18 mm (3/4 in) in length.
It was discovered as recently as 2001! I guess it just had too many options for hiding places.
From three British Virgin Islands
The other one is the Virgin Islands Dwarf Sphaero or Virgin Islands Dwarf Gecko (Sphaerodactylus parthenopion), who reaches a similar size.
It was discovered in 1964, and this time it really was hiding! They're so small, and their habitat so dry, that they must find tiny patches of humidity under rocks and leaves to prevent excessive water loss.
Not much is known about these or the other not-quite-as-small dwarf geckos. This isn't surprising. Finding them at all is a triumph in itself!