The Masked Lords of Waterdeep was the mysterious and anonymous ruling council of Waterdeep having governed the city since 1032. They oversaw the regional economy, maintained security, performed diplomacy, and held legal jurisdiction over the city and exert their will over the surrounding lands for approximately 100 miles beyond its walls.
The group was comprised of 20 members and functioned like a legislative branch, which elected, and provided checks and balances over the Open Lord.
The Open Lord of Waterdeep was the sole member of the Lords of Waterdeep whose identity was publicly known.They held a number of additional titles including Warden of Waterdeep, Overmaster of the Guilds, and Commander of the Watch. The Open Lord was also the city's chief diplomat. There was only one Open Lord at any one time, but when the previous one died or stepped down, they were replaced by a new one.
The Lords were mainly individuals with considerable wealth and influence, so it could be said that Waterdeep's government was something of an oligarchy.