Who is recognized as the current Chief Justice of the United States as of October 2023?

John Roberts is recognized as the current Chief Justice of the United States as of October 2023. He was nominated by President George W. Bush and took office in September 2005. As Chief Justice, Roberts presides over the Supreme Court, plays a crucial role in its administrative functions, and often leads the Court’s discussions on cases. His influence extends to shaping the Court's case law and its direction on various legal issues, particularly through his leadership in pivotal cases.

The other individuals mentioned have held significant roles in the Supreme Court, but they do not serve as Chief Justice. Ruth Bader Ginsburg was a prominent justice until her passing in 2020, known for her work on gender equality and civil liberties. Clarence Thomas serves as an Associate Justice and is recognized for his conservative viewpoints. Elena Kagan also serves as an Associate Justice and has made contributions to the Court’s decisions, particularly in areas of administrative law and civil rights. However, their roles do not include the authority or responsibilities that come with being Chief Justice, which is why John Roberts is the correct answer.