Christian Day and Luther Burrell are among 11 Northampton Saints players to have extended their contracts.
England centre Burrell, 29, has played 112 times for Saints since joining from Sale in 2012, while 33-year-old lock Day has featured in 203 Saints games.
Wing Ken Pisi, who has appeared 113 times, centre Juan Pablo Estelles, back-rower Ben Nutley and scrum-half Tom Kessell have signed new deals.
Tom Stephenson, who has spent this term injured, and four youngsters also stay.
Hookers Charlie Clare and Reece Marshall, lock Jordan Onojaife and Stephenson's fellow centre Rory Hutchinson complete the roll-call of names to extend their stay at Franklin's Gardens.
"Some of these players have been core members of the most successful period in the Saints' history and we believe that they have a lot to offer both in terms of their play on the pitch and leadership qualities," said Saints director of rugby Jim Mallinder.
"It's also fantastic to have a very good group of younger players who have come through the Saints academy and are now members of the first-team squad.
"It's important that we produce our own home-grown players who are able to compete for starting places alongside more experienced internationals, a combination which has been successful for us in the past."
Saints are eighth in the Premiership table, and have recently announced changes at boardroom level, with chairman Tony Hewitt to stand down and chief executive Allan Robson to retire.