From Monkey Island wiki
Michael Z. Land is the in-house composer at LucasArts responsible for the many memorable tunes of the Monkey Island series. He has been involved or credited in all five games and was responsible for creating the iMuse sound-system, with Peter McConnell, which was used in all SCUMM based LucasArts games since its inception in Monkey Island 2: LeChuck's Revenge.
He was the principal composer for the first three games and Tales of Monkey Island. His involvement was considerably smaller in Escape from Monkey Island, which was also scored by Clint Bajakian, Peter McConnell, Anna Karney and Michael Lande.
Land's compositions in the first two games were faithfully re-created for the Special Editions by Jesse Harlin.