Olive Grass Racer 
Olive House Snake 
Olive Keelback 
Olive Mountain Keelback 
Olive ridley sea turtle 
Olive Sand Snake 
Olive sea snake 
Olive Trapezoid Snake 
Olive tree skink 
Oliver's Parrot Snake 
Orange-collared keelback 
Orange-lipped Keelback 
Orange-sided Bar-lipped Skink 
Orange-winged Flying Lizard 
Oriental Garden Lizard 
Oriental Long-tailed Grass Lizard 
Oriental ratsnake 
Oriental Whipsnake 
Oriental wolf snake 
Orinoco crocodile 
Ornate 
Ornate Cat-eyed Snake 
Ornate flying snake 
Ornate Girdled Lizard