For the Starfleet cadet with a similar sounding name, please see Rader.
Vader was the name of a resident of Caldos colony who had passed away on the 23rd of September in the year 2242.
Vader's gravestone was in the same cemetery where Felisa Howard was laid to rest in 2370. In that year, the area around Vader's grave was the scene of a battle between Felisa's granddaughter Beverly Crusher and an anaphasic lifeform named Ronin. (TNG: "Sub Rosa")
This character was only mentioned in writing.