Northern Western Ghats vine snake 
Northwestern garter snake 
Oligodon everetti 
Olive Forest Racer 
Olive House Snake 
Olive Keelback 
Olive Mountain Keelback 
Olive Trapezoid Snake 
Oliver's Parrot Snake 
Orange-collared keelback 
Orange-lipped Keelback 
Oriental ratsnake 
Oriental Whipsnake 
Oriental wolf snake 
Ornate Cat-eyed Snake 
Ornate flying snake 
Ornate Snail-eating Snake 
Oxyrhopus guibei 
Painted Bronzeback 
Palmer's snail-eater 
Papua New Guinea Montane Keelback 
Paradise flying snake 
Parrot snake 
Perinet Night Snake