Jack Cornelsen (ジャック コーネルセン, Jakku Kōnerusen, born 13 October 1994) is a professional rugby union player who plays as a number eight for Japan Rugby League One club Saitama Wild Knights.

Born in Australia, he represents Japan at international level after qualifying on residency grounds.

[2] Cornelsen received his first call-up to his adopted country's wider training squad in April 2021, ahead of British and Irish Lions test.

[3] On 24 May, he was named in the 36-man squad for the match against the Sunwolves and tour of Scotland and Ireland.

This biographical article relating to Australian rugby union is a stub.