Konstantinos Atreides

Konstantinos Atreides (79 BG-10 BG) or Costin was the youngest son of Demetrios Atreides, named for the Emperor Sheuset I father.

He became Baron Menelaus the year before he died in 11 BG.

Discrepancy
In Legends of Dune the ancestor of House Atreides and rival of Abulurd Harkonnen/XD who fought in the Battle of Corrin/XD is named Vorian instead of Demetrios.Vorian has only two sons, the twins Estes and Kagin instead of three sons names Pausanias, Theseus and Konstantinos