Thomas Watt Hamilton (born May 10, 1952) was the man responsible for the Dunblane Massacre, which is regarded as one of the worst mass murders involving firearms in the United Kingdom - he killed 16 pupils as well as their teacher, before turning the gun on himself in what is known as a murder-suicide.

Hamilton's motives remain unknown, though there were complaints to police regarding his suspicious behaviour towards the young boys who attended the youth clubs he directed. There were suspicions prior to the massacre that Hamilton's interest in boys was paedophilic with more than one complaint being made regarding him having taken photographs of semi-naked boys without the parents' consent.

Hamilton had been a Scout leader with the 4th/6th Stirling and 24th Stirlingshire troops of the Scout Association. Several complaints were made about his leadership, notably including two occasions when Scouts were forced to sleep with Hamilton in his van during hill-walking expeditions. Hamilton's Scout Warrant was withdrawn on 13 May 1974, with the County Commissioner stating that he was "suspicious of his moral intentions towards boys".

He claimed in letters that rumours about him led to the failure of his shop business in 1993, and in the last months of his life he complained again that his attempts to organise a boys' club were subject to persecution by local police and the scout movement. Among those to whom he complained were local MP Michael Forsyth and Queen Elizabeth. In the 1980s, another MP, George Robertson, who resided in Dunblane, had complained to Forsyth about Hamilton's local boys' club, which his son had attended. On the day following the massacre, Robertson spoke of having argued with Hamilton "in my own home".

On 19 March 1996, six days after the massacre, the body of Thomas Hamilton was cremated in privacy.