Top 10 Most Popular , Reptiles in the World.br National Reptile Day is observed everybr year on Oct. 21 to promote education andbr appreciation for reptiles everywhere. .br According to a study that analyzed page viewbr data on all of Wikipedia’s reptilian pages,br here are the top 10 most popular reptiles in the world. .br 10. Boa Constrictor.br 9. Nile Crocodile.br 8. Leatherback Turtle.br 7. American Alligator.br 6. Western Cottonmouth.br 5. Reticulate Gila Monster.br 4. King Cobra.br 3. American Saltwater Crocodile.br 2. Black Mamba .br 1.