What is Ghoul?

Ghoul is the nickname of the hero Lifestealer in Dota 2. Previously, in the days of Dota Allstars, he used the Ghoul unit model from the Undead faction. Despite the change of his official name, the old name stuck and is still actively used by players. Lifestealer's fun/alternate name in DotA was Gollum, a significant character in the "Lord of the Rings" and "Hobbit" book series. The references to Gollum are kept up in Dota 2:

• Just like written in Lifestealer's lore, Lifestealer is no longer the former self he was, but rather a possessed body. Gollum has a similar story. Once being a Hobbit, his soul got corrupted by the ring, turning into the Gollum he is now.
• Both Lifestealer and Gollum sometimes speak from themselves in plural form ("we", instead of "I"). They also talk to or about a "master".
• His rivalry line towards Tidehunter "Tidehunter…I love a bit of raw fish now and again" refers to Gollum's hate towards stewing - or the preparing in general - of fish. Gollum prefers his fish raw and "wriggling".