Sir Konstantin Sergeevich Novoselov (Russian: Константи́н Серге́евич Новосёлов, IPA: [kənstɐnʲˈtʲin sʲɪrˈɡʲe(j)ɪvʲɪtɕ nəvɐˈsʲɵləf]; born 23 August 1974) is a Russian–British physicist. His work on graphene with Andre Geim earned them the Nobel Prize in Physics in 2010. Novoselov is a professor at the Centre for Advanced 2D Materials, National University of Singapore and is also the Langworthy Professor of the School of Physics and Astronomy at the University of Manchester, and serves as President of Constructor University in Bremen, Germany.

Konstantin Novoselov was born in Nizhny Tagil, Soviet Union, in 1974. He graduated from the Moscow Institute of Physics and Technology with a MSc degree in 1997, and was awarded a PhD from the Radboud University of Nijmegen in 2004 for work supervised by Andre Geim.

Konstantin Novoselov uses the nickname "Kostya" (diminutive of the name Konstantin).

Novoselov has published 475 peer-reviewed research papers on several topics including mesoscopic superconductivity (Hall magnetometry) as of January 2024 subatomic movements of magnetic domain walls, the discovery of gecko tape and graphene.^,

Kostya Novoselov participated in the Graphene Flagship project – a €1 billion initiative of the European Commission – and was featured in the official promotion movie of the project.

Novoselov was the first Director of the National Graphene Institute and sits on the International Scientific Advisory Committee of Australia's ARC Centre of Excellence in Future Low-Energy Electronics Technologies.

Novoselov was also a recipient of a starting grant from the European Research Council.

Kostya Novoselov made it into a shortlist of scientists with multiple hot papers for the years 2007–2008 (shared second place with 13 hot papers) and 2009 (5th place with 12 hot papers).