Nacewa, 35, who has been capped 182 times for Leinster since his debut in September 2008, is bringing the curtain down on an illustrious career for the province which already includes three Heineken Cup medals, a Challenge Cup medal and a PRO12 title.
Nacewa will hang up his boots for the second time in his career after his first retirement from the sport lasted just over two years while Strauss will walk away from rugby after a 12-year professional career with the Free State Cheetahs and Leinster.
Nacewa will not be remaining in Dublin, he will return to New Zealand at the end of the season.
Isa Nacewa retired from the provincial side in 2013 following a glorious five year stint that yielded four European trophies and promised that he would not play for any other club given the bond that he formed with the Irish side.
'Warriors on the pitch and wonderful men off it, they are, in my opinion, two of the best players to have ever worn the blue jersey.
Speaking to Leinster Rugby's official website, Cullen said: "It is hard to articulate the impact that both Isa and Richardt have had on this club since their arrival".
He won 17 caps for his adopted country of Ireland, making his debut in 2012 against South Africa.
Marsh and Timmins are looking for new clubs if they are to continue playing professional rugby.
"We will also say goodbye this evening to Peadar and Cathal who have come through the Leinster pathway and are two great examples of that route and the success that can be had if you apply yourself in the right way".