The first cryptocurrency commonly credited with implementing zk-SNARKs for privacy is Zcash.
Zcash launched in October 2016 after growing out of the Zerocoin and Zerocash research projects. Its privacy system uses zk-SNARKs—succinct, non-interactive zero-knowledge proofs—to let the network verify a transaction without exposing details such as the sender, recipient, or amount in a shielded transaction.
The technology was developed by a collaboration involving researchers from Johns Hopkins University, MIT, and the Technion. Zcash’s design was derived from Bitcoin, but it added an encrypted ledger option alongside transparent addresses, so users could choose between publicly visible and shielded transactions.
Zerocoin and Zerocash are common sources of confusion. They were privacy protocols and research projects that preceded Zcash; Zcash was the launched cryptocurrency that brought the zk-SNARK-based approach into practical public use. Monero, Dash, and Verge use different privacy techniques rather than being the answer to this question.