Least Concern Invertebrate
Octopus
The shape-shifting genius of the sea
Read the guideAnimals that start with O
There are 6 animals that start with the letter O, including the Octopus, Orangutan, Orca, and more. See photos, facts, and full guides for each.
Least Concern 
Critically Endangered Mammal
Orangutan
The great ape of the Southeast Asian rainforest
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Data Deficient Mammal
Orca
The ocean's top predator
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Least Concern Amphibian
Oriental Fire-bellied Toad
The green toad with a warning-red belly
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Least Concern Bird
Ostrich
The largest and fastest bird on land
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Least Concern Mammal
Otter
The playful, water-loving member of the weasel family
Read the guideAnimals that start with O: FAQs
What animals start with the letter O?
Animals beginning with O include Octopus, Orangutan, Orca, Oriental Fire-bellied Toad, Ostrich, and 1 more.
How many animals begin with O?
Our guide currently covers 6 animals whose names start with O.