The solicitor general of the United States (USSG or SG), is an official in the United States Department of Justice who represents the federal government in cases before the Supreme Court of the United States. The solicitor general is the fourth-highest-ranking official in the Department of Justice (DOJ). The solicitor general is appointed by the president and reports directly to the United States attorney general.

The solicitor general's office argues on behalf of the federal government in almost every Supreme Court case in which the United States is a party and also represents in most cases in which the government has filed a brief as amicus curiae. In the United States courts of appeals, the solicitor general's office reviews cases decided against the United States and determines whether the government will seek review in the Supreme Court. The solicitor general's office also reviews cases decided against the United States in the United States district courts and decides whether the government will file an appeal.

The current U.S. solicitor general is D. John Sauer.

The office was created June 22, 1870 by the efforts of Thomas Jenckes, a Representative from Rhode Island, along with Dorman Eaton and William Evarts.

The solicitor general is assisted by four deputy solicitors general and seventeen assistants to the solicitor general. Three of the deputies are career attorneys in the Department of Justice. The remaining deputy is known as the principal deputy, sometimes called the political deputy and, like the solicitor general, typically leaves at the end of an administration.

The solicitor general or one of the deputies typically presents the most important cases in the Supreme Court. Other cases may be argued by one of the assistants or another government attorney. The solicitor general tends to argue six to nine cases per Supreme Court term, while deputies argue four to five cases and assistants argue two to three cases each.

The solicitor general, who has offices in the Supreme Court Building as well as the Department of Justice headquarters, has been called the "tenth justice" as a result of the close relationship between the justices and the solicitor general (and their respective staffs of clerks and deputies). As the most frequent advocate before the Court, the Office of the Solicitor General generally argues dozens of times each term. Furthermore, when the Office of the Solicitor General endorses a petition for certiorari, review is frequently granted, which is influential given that only 75 to 125 of the over 7,500 petitions submitted each term are granted review by the Court.

The solicitor general is considered an influential and knowledgeable member of the legal community with regard to Supreme Court litigation. Six solicitors general have later served on the Supreme Court: William Howard Taft (who served as the 27th president of the United States before becoming chief justice of the United States), Stanley Forman Reed, Robert H. Jackson, Thurgood Marshall, and Elena Kagan. Some who have had other positions in the Office of the Solicitor General have also later been appointed to the Supreme Court. For example, Chief Justice John Roberts was the principal deputy solicitor general during the George H. W. Bush administration and Associate Justice Samuel Alito was an assistant to the solicitor general. The last former solicitor general to be successfully nominated to the court was Justice Elena Kagan. Only one former solicitor general has been nominated to the Supreme Court unsuccessfully, that being Robert Bork; however, no sitting solicitor general has ever been denied such an appointment. Eight other solicitors general have served on the United States Courts of Appeals.^{[citation needed]}