Altcoins are "alternative" cryptocurrencies, so called because they are an alternative to the original and biggest crytocurrency Bitcoin.
Disclaimer - Listing of any Altcoin here does not imply endorsement. Altcoins can be extremely volatile, do your own thorough research before making any investment.
Polkadot
A scalable and interoperable blockchain platform. Enables cross-blockchain transfers of any type of data or asset, not just tokens. Founded by Dr Gavin Wood, formerly Ethereum co-founder and CTO.
Duck DAO
A decentralised incubator for early-stage crypto projects.