Master of Esgaroth was the title given to the elected leader of the Lake-town.
During the time of Thorin’s Quest of Erebor (TA 2941), the Master of Esgaroth was a greedy and selfish ruler whose real name was unknown; the people called him ‘Moneybags.’ When Smaug attacked the town, he fled, leaving Bard to take control of the situation. After Smaug was slain, the Master was given a significant amount of gold to repair the town. Instead, he caught ‘dragon-sickness’ and fled with his gold into the Waste, where he eventually starved to death.
The ruler after him was wiser and more popular, and Esgaroth became more prosperous under his rule.
In Peter Jackson's Hobbit films, the Master of Esgaroth will be played by Stephen Fry.