Who are four important characters in Life of Pi?

In the novel, Life of Pi, there are four important characters to Pi.

Richard Parker is a bengal tiger from Bangledesh. He is an omega animal and eventually takes to Pi's direction.

There is a zebra whose leg is broken. It's screams put everyone on edge.

Additionally, there is an orangutan. The orangutan is in shock and continues to reach out its hand to Pi.

Lastly, there is a hyena. The hyena is vicious and eventually kills the orangutan.

All of these animals are replaced symbolically by humans when Pi is taken to the police who want his story. He says that the hyena was a crazy cook who killed his mother (orangutan) and the sailor (zebra). He says that the hyena was then killed by Richard Parker (Pi's animalistic self).