Nicholas Grainger (born 3 October 1994) is an English freestyle swimmer representing Great Britain at the FINA World Aquatics Championships.

He has won two gold medals as part of a relay team at the World Championships.

[2] Grainger competed for City of Sheffield before being selected for the national team.

[5] At the 2017 World Aquatics Championships, Grainger won gold in the 4x200m freestyle with James Guy, Stephen Milne and Duncan Scott.

[6] At the 2018 Commonwealth Games held in the Gold Coast, Australia, Grainger was part of the team that won silver in the 4x200 m freestyle.