Death had always surrounded Darth Vader, in either of his lives. As a child, he watched people die in podraces. Qui-Gon, who he'd placed in his mind as a father-figure, was killed by Darth Maul. As a Padawan, his mother had died in his arms; he'd slaughtered her captors, their pets and their children. As a Jedi Knight in the Clone Wars, he had "killed" countless numbers of droids while allies fell around him.
He had slaughtered the Jedi Order, one by one, hunting them down until the only ones left were Yoda and Obi-Wan. Yoda had proved an effective foe in the game of hide-and-kill, but the former teacher of Anakin Skywalker was only left alive because he had settled on the one place that Vader would not follow him to. As his fall continued, after the destruction of the Jedi, he took out all politically-important Separatists in a single fell swoop; it had allowed Darth Sidious to dismantle the Senate and create the Empire.
Most importantly, and most hideously, he had killed his own wife. It was the one thing, the only thing, that he regretted...but he couldn't change the past, only beg forgiveness, and he didn't even try. He loved her still, though lost to him she was, and some might even say that she was lost to him from the start. It was painful, it was violent, and it was what plagued him at night: death.
He had killed Obi-Wan on the first Death Star, and several Rebel Alliance fighters outside of it. More of the rebels had been killed on Hoth, and then again in those jungles of some world or moon that he couldn't be bothered to remember. He had lifted the Emperor up with one hand, his dominant right having been taken off by his son Luke, tossing him down to his death...and that was it.
Well, not entirely. There was still the matter of his own death. It wasn't how he might have imagined it, though it's certainly how he wanted it: quiet, alone, and at peace with himself. It was nice...or as nice as death could be for a warlord and mass-murderer who was directly responsible for the obliteration of the Galactic Republic and the rise of the Empire that followed it. His body and armor had been burned, fittingly enough; a blaze of glory, holding a black symbol of evil inside of it, that would leave only the ashes.
He would have thought that death would come in battle, and more likely a space-based conflict than anything on the ground; though he'd been the galaxy's best pilot in his younger years, his personal TIE fighter didn't hold nearly the same amount of armament or maneuverability as most fighter ships. While his power was unrivaled on the ground, his mechanical limbs couldn't react with the same speed as flesh-and-blood arms or legs...so there should have been someone who managed to kill him from behind.
Yes, Darth Vader knew death well. It greeted him as an old friend when they met at last, and he couldn't have helped but feel relieved to have finally come into its home and rejoin his wife again.