William Claiborne Ferguson IV is an American politician, attorney, and former schoolteacher. He is a Democratic member of the Maryland Senate, representing the 46th legislative district since 2011, and serving as the President of the Maryland Senate since January 8, 2020. The district is composed of parts of Baltimore City.

The Maryland Senate, sometimes referred to as the Maryland State Senate, is the upper house of the General Assembly, the state legislature of the U.S. state of Maryland. Composed of 47 senators elected from an equal number of constituent single-member districts, the Senate is responsible, along with the Maryland House of Delegates, for passage of laws in Maryland, and for confirming executive appointments made by the Governor of Maryland.