Monero is a decentralized public ledger protocol whose focus is on increased privacy. It was created in 2014, with the goal of establishing a privacy focused blockchain that would allow users to send and receive transactions anonymously, and not pseudo-anonymously, like Bitcoin.
Monero uses an obfuscated public ledger that prevents anyone from determining the source, destination, or amount of payments. Unlike many other cryptocurrencies, payments and account balances on Monero remain entirely hidden. This is one reason that XMR, the Monero currency, has attracted some users that are involved with illicit activities.
Monero uses a Proof of Work consensus mechanism that requires less computing power from miners than Bitcoin does. Because of this, mining Monero has become an alternative source of revenue for some websites and apps. .

.

Grin Coin is a community driven blockchain project that aims to create a lightweight mimblewimble blockchain that will enable anonymous transactions. Grin has a Proof-of-Work consensus mechanism. Transactions are executed while hiding addresses and amounts.

ZCash is a privacy focused cryptocurrency protocol that enables users to make transactions anonymously. Users to hide the sender, receiver, and amount of every transaction. ZCash has several high profile advisers and investors, including: Roger Ver, Gavin Andresen, and Vitalik Buterin.
ZCash has a fixed supply of 21 million coins; 20% of which will be allocated as a founders reward that is split between investors and developers. This founders reward has been the subject of controversy and has led to a fork of the ZCash protocol.