Pyromaniac (noun)

A person who has an abnormal desire to set things on fire.

Origin:

From greek pyr (fire) + mania (madness, frenzy).

Examples:

1. The police suspected the fire was set by a pyromaniac.
2. The arsonist was diagnosed as a pyromaniac.
3. The fire department was on the lookout for a pyromaniac.
4. His obsession with fire made him a pyromaniac.
5. The pyromaniac was arrested for setting the fire.