Everyone in the crypto space knows about Tether. They primarily issue the stablecoin known as USDT(they also issue EURT, CNHT, XAUT but nobody really cares about those). They claim to always fully backed 1 to 1 with real currency cash and cash equivalents(T-bills, bonds etc.). Also, from time to time, may include other assets and receivables from loans made by Tether to third parties, which may include affiliated entities.

How they claim to back their tokens accessed on 27 Feb 2021