Christian Decker of Blockstream made the first full, secure Lightning payment on a non-test network, and the first Lightning payment on Litecoin, sending a microscopic payment not normally possible or economic on a blockchain, fully settled in a fraction of a second. Early adopters using the lightning network on the mainnet instead of testnet with larger than needed amounts of Bitcoin, despite warnings that it was still experimental, led to the term "reckless" being used during this period in bitcoin's history.
This
video documents the (most likely) first non-testnet Lightning channel being established on Litecoin.