William I of Sicily, also known as William the Bad, was the King of Sicily from 1154 until his death in 1166. He was the son of Roger II of Sicily, the founder of the Sicilian kingdom. William's reign was marked by internal strife and challenges to his authority, as he struggled to maintain control over a diverse population. Despite his nickname, William made efforts to strengthen the kingdom's administration and economy. He faced opposition from the nobility and dealt with revolts, but he also promoted trade and cultural exchanges. His reign laid the groundwork for future developments in the region.