Daniel Tammet, born as Daniel Paul Corney on 31 January 1979, is an English writer and savant. He is renowned for his extraordinary abilities in mathematical calculations and language learning, which are associated with Asperger syndrome and savant syndrome.

His memoir, Born on a Blue Day (2006), details his early life with these conditions and was named a "Best Book for Young Adults" in 2008 by the American Library Association's Young Adult Library Services magazine. Tammet's second book, Embracing the Wide Sky, was among France's best-selling books of 2009, and his third book, Thinking in Numbers, was published in 2012 in the United Kingdom and in 2013 in the United States and Canada.

His works have been translated into over 20 languages. In 2012, he was elected as a fellow of the Royal Society of Arts. Tammet is also the subject of the award-winning documentary The Boy with the Incredible Brain.