Kakuzu: Takigakure

Kakuzu  was an S-rank missing-nin from the 'Village of Waterfall' and a member of Akatsuki, he was partnered with Hidan. Kisame Hoshigaki jokingly referred to them as the Zombie Combo due to the fact that, in a sense, they both were immmortals. Within the organisation itself, Kakuzu acted as the organisation's Bank
When under the service of hidden village of Waterfall as an elite ninja, Kakuzu took on a mission to assassinate Hashirama Senju. This mission, however, ended in failure. Despite the insurmountable danger faced on the mission, what awaited his return to his village was the stigma and harsh punishment associated with the failure of his objective. In his flight from the village, Kakuzu killed the village elders, took their hearts, and fled with knowledge of the village's most prized forbidden techniques. He made a living off bounty hunting on the black market, and tearing out the still-beating hearts of powerful shinobi to extend his own lifespan and strength

Also at some time in the past, he apparently encountered the Gold and Silver Brothers and witnessed Kinkaku and Ginkaku

Some time after his defection, he joined Akatsuki, and was given a number of partners, most of whom he killed, due to his short temper. This is why he was eventually partnered with Hidan, whom he could not kill because of his immortality.
In the anime, Kakuzu and Hidan met with Sasori and Deidara to discuss their new missions assigned by Akatsuki. After Kakuzu said they had a choice between a money-making mission and a war-mission, he chose the money mission after Sasori and Deidara showed no interest in it.