The Steele dossier, also known as the Trump-Russia dossier, is a political opposition research report written by Christopher Steele, a former British MI6 intelligence officer. It was published without permission as an unfinished raw intelligence report. The dossier contains allegations of connections between Donald Trumps 2016 presidential campaign and the Kremlin, as well as allegations of salacious sexual activity that Trump supposedly engaged in at a Moscow hotel.

The dossier is based on information from witting and unwitting anonymous sources known to counterintelligence specialist Christopher Steele. Some were later revealed. Steele was hired to compile the dossier by Washington DC-based research firm Fusion GPS, which was itself retained by a law firm on behalf of Trumps political opponents, Hillary Clinton, the Democratic candidate in the 2016 election, and the Democratic National Committee.

The dossier was never intended to be public because it was unfinished raw intelligence and could have "compromised sources and methods". Steele was also worried about the safety of his source network, and he expressed concern that if Trump won the election, the new FBI director, and other agency heads appointed by Trump, might be more loyal to Trump "and could decide to take action against Steele and his source network".

The dossier has been the subject of numerous investigations and lawsuits, and many of its central allegations have been discredited. However, some of Steeles allegations have been proven true, including the Trump campaigns collusion with Russia. The dossier has also been used by the FBI to obtain surveillance warrants on a top Trump aide.

In 2022, the primary source for allegations in the dossier, Igor Danchenko, was acquitted of lying to the FBI about the dossiers sources. Special Counsel John Durham, who was appointed by Trumps attorney general in 2019 to look into the FBIs inquiry of ties between Russia and Trumps 2016 presidential campaign, brought the charges against Danchenko.