A brown bear, an cattle, a chicken, an bottlenose dolphin, a guineafowl, an wild pig.

Escherichia coli is a microscopic single-celled organism, and a prokaryote as well.

Amoebae are single-celled eukaryotes

Polypore fungi and angiosperm trees are large many-celled eukaryotes.

Phylogenetic tree of life (Carl Woese). Viruses do not appear here because there is no evidence of how they relate to the other three kingdoms of life

An organism is an individual living thing. It is easy to recognize a living thing, but not so easy to define it. Animals and plants are organisms, obviously. Organisms are a biotic, or living, part of the environment. Rocks and sunshine are parts of the non-living environment.