Slytherin, early 1970s (deduction from GF27). Strictly speaking, the book only specifies that Rabastan’s brother and sister-in-law were Slytherins, since Sirius was speaking of the Lestranges as “a married couple.” – MLW
A Death Eater; brother of Rodolphus Lestrange (GF30, OP6). Rabastan and his brother Rodolphus were captured by the Ministry of Magic after their attack on the Longbottoms (November or December 1981) and given a life sentence in Azkaban (GF27, GF33); however, they escaped when the Dementors turned against the Ministry in January 1996 (OP25) .
Rastaban = from an Arabic phrase meaning "the serpent's head;" a name of Beta Draconis, one of the stars in the constellation Draco that is visible in Earth's night sky but relatively dim, just as this Death Eater tends to be overshadowed by his formidable sister-in-law.