Jacob Jeremiah Sullivan (born 1976) is an American senior government official who serves as the National Security Advisor to U.S. President Joe Biden. He was previously senior policy advisor to Hillary Clinton's 2016 presidential election campaign, with expertise in foreign policy, and Deputy Chief of Staff at the Department of State. Sullivan was also a senior advisor to the U.S. government for the Iran nuclear negotiations and a visiting professor at Yale Law School.

Sullivan worked in the Obama administration as Deputy Assistant to the President and National Security Advisor to U.S. Vice President Joe Biden. He also served as the Director of Policy Planning at the U.S. Department of State, and as Deputy Chief of Staff to U.S. Secretary of State Hillary Clinton.

On November 23, 2020, Biden announced that Sullivan would be appointed National Security Advisor. He took office effective January 20, 2021.

Denis Richard McDonough (born December 2, 1969) is an American political and government official. He was the 26th White House Chief of Staff, succeeding Jack Lew at the start of President Barack Obama's second term, and serving in that role throughout that term.

Previously, McDonough served as Deputy National Security Advisor from 2010 to 2013 and as Chief of Staff of the National Security Council from 2009 to 2010.

President Joe Biden has nominated McDonough to serve as United States Secretary of Veterans Affairs in his administration.

Alejandro Nicholas Mayorkas (born November 24, 1959) is an American lawyer and government official. During the Obama administration, he served in the Department of Homeland Security, first as Director of U.S. Citizenship and Immigration Services (2009–2013) and then as Deputy Secretary (2013–2016).

In 2016, Mayorkas became a partner at Wilmer Cutler Pickering Hale and Dorr, a Washington, D.C., law firm. President Joe Biden has nominated Mayorkas as Secretary of Homeland Security in his Cabinet.

Lloyd James Austin III (born August 8, 1953) is an American retired four-star Army general who has been the United States secretary of defense since January 22, 2021. Austin previously served as the 12th commander of United States Central Command (CENTCOM). Austin was the first black commander of CENTCOM,and is the current secretary of defense.

Before CENTCOM, Austin was the 33rd vice chief of staff of the United States Army from January 2012 to March 2013, and the last commanding general of United States Forces – Iraq Operation New Dawn, which ended in December 2011. He retired from the armed services in 2016 and joined the boards of Raytheon Technologies, Nucor, and Tenet Healthcare.

Merrick Brian Garland (born November 13, 1952) is an American lawyer, jurist, and attorney general designate who serves as a United States circuit judge of the United States Court of Appeals for the District of Columbia Circuit. He has served on that court since 1997. President Joe Biden has nominated Garland for the position of United States attorney general.

A native of the Chicago area, Garland attended Harvard University for his undergraduate and legal education. After serving as a law clerk to Judge Henry J. Friendly of the United States Court of Appeals for the Second Circuit and Justice William J. Brennan Jr. of the Supreme Court of the United States, he practiced corporate litigation at Arnold & Porter and worked as a federal prosecutor in the United States Department of Justice, where he played a leading role in the investigation and prosecution of the Oklahoma City bombers.

President Barack Obama, a Democrat, nominated Garland to serve as an associate justice of the Supreme Court in March 2016 to fill the vacancy created by the death of Antonin Scalia. Despite Republicans themselves having spent years suggesting Garland as an acceptable Democratic choice, the Senate Republican majority refused to hold a hearing or vote on this nomination made during the last year of Obama's presidency, with the Republican majority insisting that the next elected president should fill the vacancy. The unprecedented refusal of a Senate majority to consider the nomination was highly controversial. Some Republican lawmakers suggested leaving the court with just eight seats if Hillary Clinton were to be elected, saying they would block Garland or any other nominee and keep the seat vacant for at least another presidential term. Garland's nomination lasted 293 days (the longest to date by far) and expired on January 3, 2017, at the end of the 114th Congress. The seat for which Garland was nominated was eventually filled by Neil Gorsuch, appointed by President Donald Trump.

William Joseph Burns (born April 4, 1956) is an American diplomat, who has since 2014 held the position of the president of the Carnegie Endowment for International Peace and a former United States deputy secretary of state (2011–2014). He retired from the US Foreign Service in 2014 after a 33-year diplomatic career.

Burns previously served as Ambassador of the United States to Jordan from 1998 to 2001, Assistant Secretary of State for Near East Affairs from 2001 to 2005, Ambassador of the United States to the Russian Federation from 2005 to 2008, and Under Secretary of State for Political Affairs from 2008 to 2011.

In January 2021, Joe Biden nominated Burns to head the Central Intelligence Agency.