Shadow Wolves
The Shadow Wolves are (or rather were) a chapter of the Adeptus Astartes.
They were listed as being successors of the Imperial Fists but author Aaron Dembski-Bowden, the creator of the chapter, has confirmed that they were meant to represent the concept of loyalist Luna Wolves as a tribute to his wife Katie (who is a fan of the Luna Wolves).
Chapter History
966 M41
One of their strike cruisers, the Purest Intent, is captured by the Orks.
987 M41
The last of the Shadow Wolves are slain by the Tyranid xenos at the battle for Varadon, the chapter's homeworld, a few weeks after the chapters monastery had been overwhelmed. The chapters survivors attempted to link up with the Black Templars but were surrounded. The last battle brother alive planted the chapter's banner even as he died.
998 M41
The Purest Intent crashed near Helsreach during the opening void battle in the Third War for Armageddon and was cleansed of Ork survivors by the Black Templars under Reclusiarch Grimaldus.
999 M41 A strike team of Shadow Wolves arrived on Cadia to help its defense just prior to the Fall of Cadia during Abbadon's 13th Black Crusade.
Sources
Helsreach: Warhammer 40,000