Usman Khan (Urdu: عثمان خان; 10 March 1991 – 29 November 2019), also known as Abu Saif, was a Pakistani Islamic terrorist who on 29 November 2019, murdered two people near London Bridge before being subdued by civilians and fatally shot by City of London Police.

Born in Stoke-on-Trent, England, to parents of Pakistani descent, Khan's education included attendance at Haywood High School. A portion of his teenage years was spent in Pakistan, where, prior to his December 2010 arrest, he visited the Federally Administered Tribal Areas, as noted in a 2013 report by the British Parliament's Independent Reviewer of Terrorism Legislation. Khan's involvement with al-Muhajiroun, militant network based in Saudi Arabia, led to his role as a community organiser, notably arranging a Sharia conference in 2009.

In 2008, following a raid on his Stoke-on-Trent residence by counter-terrorist police, Khan faced scrutiny but denied terrorist affiliations in interviews with the BBC and a local newspaper under a pseudonym. Despite a 20-month inquiry, no charges were filed against him.

Upon returning from Pakistan, Usman Khan was arrested in 2010 as part of a group of nine individuals targeted by MI5’s Operation Guava. In 2012, all members of this group pleaded guilty to charges of terrorism inspired by Al-Qaeda. Their plans included bombing significant locations in the UK such as the London Stock Exchange, the Houses of Parliament, the US embassy, two rabbis at two synagogues, the Dean of St Paul's Cathedral, the home of then London Mayor Boris Johnson, as well as proposing to establish a terrorist training camp in land owned by Khan’s family in Pakistan-administered Kashmir. The group also engaged in planning meetings and made preparations for travel related to terrorist activities, with intentions to carry out further attacks in the UK upon returning from the proposed camp in Kashmir.

Khan proposed to raise funds in the UK rather than overseas, arguing that supporters in the UK earned in a day what donors in Kashmir earned in a month. He added: "On Jobseeker's Allowance we can earn that, never mind working for that." His home bugged by MI5, he was recorded calling non-Muslims "dogs". Following his arrest, Khan admitted travelling to the plotter's 2010 tactical meetings in Cardiff in November and in Newport in December. Khan's plans to build a terror-training camp in Kashmir never materialised and "there was no evidence that there was any real funding to build it". The group had formed in October. The terror network's organisational chart was found in Khan's home. In addition to confessing to terrorism planning, Khan admitted terrorism fundraising and possession of the Al Qaeda magazine Inspire.

Following his arrest, evidence of Khan’s advanced knowledge in field craft was noted, highlighting his significant role within the group. In 2012, he was sentenced to imprisonment for public protection and an indeterminate period in prison with a minimum term of eight years, reflecting the judge’s assessment of Khan and his associates from Stoke-on-Trent as exceptionally committed jihadists operating at a level of seriousness and effectiveness above that of their co-defendants.

Khan was originally sentenced to indefinite imprisonment for public safety. This sentence, however, was overturned in 2013 when Khan, alongside Nazam Hussain and Mohammed Shahjahan, appealed. The Court of Appeal, led by Lord Justice Leveson, re-evaluated the perceived threat level of these individuals compared to their co-defendants, resulting in a reduced sentence of 16 years with eligibility for automatic release after eight. Upon completion of this term, Khan was released from Whitemoor prison in December 2018 under standard licence conditions, which included probation supervision. Stafford Borough Council, with support from multiple agencies, arranged suitable housing following his release.

During his imprisonment, Khan engaged in the Healthy Identity Intervention Programme, aimed at rehabilitating terrorism offenders. This participation continued post-release with the Desistance and Disengagement Programme, focusing on tackling terrorism's root causes. Khan's involvement in these programmes led to his recognition as a rehabilitation "success story" by a Cambridge University programme, culminating in a case study feature. Khan would later tragically kill two individuals associated with the Cambridge University programme. Following these events, discussions emerged regarding the potential overestimation of recidivism fears, with a paper published by the CTC Sentinel in April 2020 described Khan and another recent terrorism recidivist as an atypical example, noting a recidivism rate of less than 5% among terrorists.