Frog

Frogs were amphibious creatures native to Earth. The word was also an epithet typically hurled by the British against the French.

Earth frogs
In June 1816, Percy Shelley recalled how Galvani had experimented on frogs by subjecting them to electromagnetic spark, which had caused their legs to move. (AUDIO: Mary's Story)

When the Axons offered axonite to the people of Earth, they used it to make a frog grow in size, demonstrating how it could be used to solve world hunger. (TV: The Claws of Axos)

The Thirteenth Doctor was photographed at some point running away from a giant frog in front of Buckingham Palace. (PROSE: Rose)

Grace O'Brien liked frogs. As a result, both Ryan Sinclair and Graham O'Brien got her a necklace with a frog on it, unaware that the other had decided on the same thing. In order to verify that the Solitract construction of Grace was her, he asked her about the frog necklace. Due to Grace liking frogs, the Solitract took the form of one when talking to the Thirteenth Doctor. (TV: It Takes You Away)

Other frogs
The Urbankans resembled frogs, as noted by the Fifth Doctor and Tegan Jovanka. On Monarch's ship, frogs were used for their poison by the Monarch. The poison had the power to shrink living people. (TV: Four to Doomsday)

Josiah W. Dogbolter was half-frog, half-man. (COMIC: The Moderator)

On an Earth-like planet, the First Doctor, John and Gillian met a race of hat-wearing talking frogs and helped them catch a shark that was trying to eat them. The frog people helped them search for the Doctor's TARDIS when it disappeared. (COMIC: Shark Bait)

On the planet Chloris, the Fourth Doctor suggested that a giant frog was responsible for laying a giant egg there. (TV: The Creature from the Pit)

One of the Eleventh Doctor's fezzes was eaten by a slime-frog on the Third Moon of Puggo. (COMIC : A Wing and a Prayer)

There were cave frogs on Leela's home planet. (AUDIO: The Man at the End of the Garden)