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A chapter of the Adeptus Astartes from Warhammer 40K. First introduced in the PC RTS game Dawn of War, the chapter have since appeared in both the tabletop and other 40k games as well. The chapter is known from their red armor and their emblem, a raven with a blood drop on its chest.
While generally well received amongst (most of) the Imperium for their protective nature over civilians and eagerness to deal death to the enemies of the Imperium, the Techpriests of Mars and the Inquisition due to their voracious appetite for knowledge, learning and artifacts in particular, the Blood Ravens have a mixed reputation amongst the other Space Marine chapters due to both their strategies (favoring extensive recon, meticulous planning and pinpoint assaults on key enemy vulnerabilities) and their Chapter-wide tendency to produce almost unprecedented numbers of psykers and Librarians. The Space Wolves (who favor strategies involving charges and overwhelming the foe in massed melee) infamously do not tolerate Blood Raven procedures at all, with physical altercations being recorded between the two chapters at command-level meetings.
As a second-founding chapter with no official records prior to M37K, the Blood Ravens do not (again officially) have a recognizable Primarch. However, their color scheme, tendency to produce psykers and culture surrounding the acquisition of knowledge strongly suggest that they are descendants of Magnus the Red, making them loyalists of the Thousand Sons traitor legion. This would also make them an indirect relative chapter of the Grey Knights due to sharing a Founder in Janus.
As the Blood Raven arsenal contains some phenomenally unlikely artifacts (Gear belonging to the Custodes and Primarchs to name but a few) that would have been under enough security to make their theft near impossible, the Blood Ravens gained the fandom reputation of being able to perform implausible acts of indefinite borrowing, such as swapping places with a Land Raider's driver while he's still inside the cockpit, acquiring Bjorn the Fell-handed's Dreadnaught for combat use (with Bjorn catching on quickly to his new circumstances and happily embracing the chance to go back to war) and involuntarily renting the Golden Throne of Terra.
The chapter have been jokingly called "The Bloody Magpies" by fans due to how the chapter are constantly gifted (or 'gifted', due to those same chapters not having any records stating that they ever gave the Ravens anything) rare, powerful weapons and gear from other older chapters.
Due to their memetic shenanigans, gateway status to the 40k world and generally being a interesting chapter, the Blood Ravens are well-regarded amongst the fandom - even if the jokes about rampant theft get a little repetitive.
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