Some Puranas explain the origins of different beings other than the humans.

The Vishnu Purana explains that once when Brahma was in a foul mood, Hunger emerged from Brahma.

From this Hunger, some beings and creatures had emerged. These creatures looked hideous.

Brahma put the lean and thin creatures that had emerged into the darkness.

In the darkness, some of these creatures rushed to Brahma, pleading with the Creator God. "Please save us."

In Sanskrit, 'Raksha' means preserve or save.

As these beings had asked Brahma for raksha, they came to be known as Rakshasas.

A female Rakshasa was a Rakshasi.

Interestingly, the Vishnu Purana also mentions that from the same Hunger in the darkness, not all creatures asked Brahma to be saved.

Some wanted to eat because they were hungry.

In Sanskrit, Yaksa is to eat.

So these beings that wanted to eat came to be known as Yakshas.

However, over time, Yakshas became the beings of the higher realms and protected all the natural elements.

Rakshasas generally came to be known as creatures that terrorised humans.

There were many good Rakshasas too, but over time, Rakshasas generally came to be projected as cannibalistic beings who were well-versed in magic and were phenomenally powerful.

During the times of the Mahabharata, Rakshasas were cannibalistic beings residing in the forests, living in caves or trees, and the Rakshasas were hideous to look at, though they could change their form at will.