Tomas Robert Lindahl FRS FMedSci (born 28 January 1938) is a Swedish scientist specialising in cancer research. In 2015, he was awarded the Nobel Prize in Chemistry jointly with American chemist Paul Modrich and Turkish chemist Aziz Sancar for mechanistic studies of DNA repair.

Lindahl was professor of medical chemistry at the University of Gothenburg 1978-82. He moved to England and joined the Imperial Cancer Research Fund (now Cancer Research UK) as a researcher in 1981. From 1986 he was the first Director of Cancer Research UK's Clare Hall research institute in Hertfordshire. Since 2015 this has been part of the Francis Crick Institute.

When the Royal Society elected him as a Fellow, his achievements were extraordinary (though rather technical):