Alun Wyn Jones will remain on course to break the all-time record for international caps after extending his Welsh Rugby Union contract.
Scotland's record appearance holder Ross Ford has confirmed his retirement ahead of plans to go into strength and conditioning coaching.
Stephen Larkham has agreed to a new challenge with Irish province Munster, signing a deal until June 2022.
Ireland's most decorated player, Rob Kearney, is sure of playing his 15th professional season in his home country.
Leinster failed to read the script as Stuart Hogg's final Glasgow Warriors match ended in a painful Pro14 final defeat.
Cian Healy says he is "part of something bigger than just a rugby team" representing Leinster and Ireland.
Munster gave it a great go, but Leinster have the chance to be crowned Pro14 champions once again.
Tommy Seymour scored two of his team's seven tries as Glasgow Warriors routed Ulster in the first Pro14 semi-final.
Exeter Chiefs-bound Scotland full-back Stuart Hogg knows Glasgow Warriors will have to be at their best to see off Ulster.
Nicky Smith was linked with the likes of Cardiff Blues, Sale Sharks and Gloucester, but the prop is staying with his home region.