Roger Jason Stone (born Roger Joseph Stone Jr.; August 27, 1952) is an American right-wing political activist, consultant and lobbyist. He is a prominent consultant and lobbyist within the New Right, and Donald Trump's longest-serving political adviser. He was the subject of widespread media coverage for the Mueller special counsel investigation and his alleged involvement with and connections to Russian interference in the 2016 U.S. presidential election as a consultant for the Trump campaign.

Since the 1970s, Stone has worked on Republican campaigns, including those of Richard Nixon, Ronald Reagan, Jack Kemp, Bob Dole, George W. Bush, and Trump. He co-founded a lobbying firm with Paul Manafort and Charles R. Black Jr. The firm became Black, Manafort, Stone and Kelly (BMSK) in 1984. BMSK became a top lobbying firm, leveraging White House connections for high-paying clients, including U.S. corporations, trade associations, and foreign governments. Stone's style has been described as "a renowned infighter", "a seasoned practitioner of hard-edged politics", "a Republican strategist", and "a political fixer". Stone has called himself "an agent provocateur". He has described his political modus operandi as "attack, attack, attack—never defend" and "admit nothing, deny everything, and launch a counterattack", all evocative of associate Roy Cohn.