The Common Frog, Rana temporaria also known as the European Common Frog or European Common Brown Frog is found throughout much of Europe as far north as well north of the Arctic Circle in Scandinavia and as far east as the Urals, except for most of Iberia, southern Italy, and the southern Balkans. The farthest west it can be found is Ireland, where it has long been thought erroneously to be an entirely introduced species.

Adult Common Frogs have a body length of 6 to 9 centimetres (2.5 to 3.7in) and their backs and flanks vary in colour, with olive green grey-brown, brown, olive-brown, grey, yellowish or rufous possible. However, Common Frogs are known to be able to lighten and darken their skin in order to match their surroundings. It is also not unknown for more unusual colouration- both black and red individuals have been found in Scotland, and male Common Frogs have been known to turn greyish blue in the mating season (video on page). Additionally, albino Common Frogs have been found with yellow skin and red eyes. Their average weight is 22.7g (0.8 oz). Females are usually slightly larger than males.