Johnny Sexton will be Ireland's captain under Andy Farrell, who has named five uncapped players in his first squad for the Six Nations.
Teenage wing Louis Rees-Zammit is among five uncapped players in new Wales head coach Wayne Pivac's squad for the Six Nations.
Stuart Hogg has been named Scotland captain for the Six Nations and Gregor Townsend has included six uncapped players in his squad for the tournament.
England revealed a new-look coaching team to support Eddie Jones heading into the Six Nations.
Italy interim coach Franco Smith has named his first squad as he assesses his options ahead of the Six Nations, with Alberto Sgarbi recalled after a six-year absence.
Ian Foster knows he will have to "reinvent" himself after stepping up to replace Steve Hansen as head coach of New Zealand.