What was the name of the 2016 attack that drained ether from Ethereum’s DAO?

The 2016 attack that drained ether from Ethereum’s DAO is known as the DAO hack.

The DAO was a decentralized investment organization built as a smart contract on Ethereum. In June 2016, an attacker exploited a flaw in its code involving recursive calls and moved approximately 3.6 million ether into a child DAO. At the time, the amount represented a substantial share of all ether in circulation.

The incident triggered an intense debate over immutability, governance, and whether a blockchain community should intervene after a smart-contract exploit. Ethereum’s community ultimately adopted a hard fork that returned affected funds through a recovery mechanism. The unforked chain continued as Ethereum Classic, while the forked chain retained the Ethereum name.

The DAO hack is often confused with later exchange or bridge failures. It was specifically a smart-contract exploit against The DAO in 2016, not a compromise of the entire Ethereum protocol or of every Ethereum account.