Sir Steven Charles Cowley (born 1959)[citation needed] is a British theoretical physicist and international authority on nuclear fusion and astrophysical plasmas.

He has served as director of the United States Department of Energy (DOE) Princeton Plasma Physics Laboratory (PPPL) since 1 July 2018.

[6] and head of the EURATOM / CCFE Fusion Association and chief executive officer of the United Kingdom Atomic Energy Authority (UKAEA).

[7] Cowley won a scholarship to Corpus Christi College, Oxford and graduated with a Bachelor of Arts degree in Physics in 1981.

His biography reads; Steven Cowley is a leading plasma theorist and currently chief executive officer at the UK Atomic Energy Authority.

Steven is leading the UK's participation in ITER, an experimental reactor that is set to make nuclear fusion commercially viable.

Over the last twenty years he has played a leading role in developing the multi-scale approach to computing the plasma turbulence in fusion experiments.

[34] In July 2019, Cowley was awarded the honorary degree of Doctor of Science (honoris causa) by the University of Lancaster for his standing as the international authority on fusion energy.