By Lawrence Hurley

WASHINGTON (Reuters) - Vice President-elect Mike Pence will be sworn into office on Jan. 20 by U.S. Supreme Court Justice Clarence Thomas, a conservative legal icon reviled by many liberals.

Thomas's role was included in the official program for Republican President-elect Donald Trump's inauguration posted online by the Joint Congressional Committee on Inaugural Ceremonies.

Trump will be sworn in by conservative Chief Justice John Roberts. The nation's chief justice usually swears in the president but an incoming vice president traditionally picks someone else to administer the oath of office.

Vice President Joe Biden was sworn in by liberal Justice John Paul Stevens in 2009 and liberal Justice Sonia Sotomayor in 2013.

Thomas, 68, is the second black justice to serve on the Supreme Court and is one of its most conservative members.

Nominated by Republican President George H.W. Bush, Thomas joined the court in 1991 after contentious Senate confirmation hearings involving sexual harassment allegations against him made by a former federal government colleague, Anita Hill.

In October, after controversy erupted over allegations Trump had fondled numerous women and boasted about it, a female corporate lawyer from Alaska accused Thomas of groping her in 1999, a charge Thomas called "preposterous" and untrue.

After taking office, Trump will nominate a justice to serve alongside Thomas on the Supreme Court to fill the vacancy created by the death of another conservative, Justice Antonin Scalia, in February 2016.

Republicans who control the U.S. Senate declined to act on President Barack Obama's nominee to fill the position, Merrick Garland.

(Reporting by Lawrence Hurley; Editing by Will Dunham)