The Executioners believe that their Chapter was created for the sole task of seeking out and slaughtering Mankind's foes rather than undertaking any more defensive or strategic purpose. This Chapter is bellicose and almost barbarous in nature, and disdains martial trappings and the ordered obedience of other more stalwart Codex-compliant Chapters such as the Ultramarines and their own forebears, the Imperial Fists. The Executioners have made up for this "flaw" by gaining a fearsome reputation for sheer undaunted endurance and destructive wrath. Their primary goal and purpose as a Chapter is a simple one; to extinguish the lives of those that would have the audacity to contest the Imperium's manifest destiny or threaten humanity. The Executioners literally see themselves as the Emperor's chosen headsmen, and His judgement theirs to enact on His behalf.
This Chapter's ancient ways and beliefs are rooted in the twin Feral Worlds of Stygia-Aquilon, from which they have long recruited their Neophytes. By the laws and traditions of their Chapter, each Executioners Battle-Brother is expected to forge his own path to glory and become worthy of remembrance in the great chronicles that have been kept by successive generations of the Chapter's Chaplains, or "Death-Speakers" as they are known amongst the Executioners. It is the Death-Speakers' task to recount the slaughter-tallies of the Chapter's honoured dead during holy feasts and memorial ceremonies held deep within the catacombs of their fortress-monastery, the Darkenvault. Their second but equally important task is to keep order within the ranks of this often fractious Chapter. Consequently, the Executioners maintain an unusually high number of Chaplains, with three Death-Speakers assigned to each company by tradition. They report to the overall Reclusiarch, known within the Chapter as the Lord Speaker of the Dead. As part of their duties, the Death-Speakers are responsible for maintaining precise records of the Chapter's battles, so that lessons of both victories and defeats are never lost for future warriors of the Chapter.
It is only by right of bloodshed, by taking the lives of the Emperor's enemies, that an Executioners Battle-Brother can be granted the honour of a place in the Chapter chronicles, and thereby earn the respect of their fellow Space Marines and attain rank and honour within the Chapter. The Battle-Brothers of this Chapter have an intractable and ambitious nature. Quick to anger, an Executioners Astartes is taught to avenge slights to their honour with blood, even amongst their own, but unlike the few other Chapters where such behavior is tolerated or even encouraged (such as the Space Wolves or Marauders for example), there is little that passes in the way of brawling or boisterous competition amongst the Executioners Astartes, for all such battles are to the maiming or the death of those involved. In their extreme view, honour demands no less.
Another disturbing eccentricity of the Chapter to outside observers is the tendency for the Executioners' Astartes to carry trophies from the battlefield, taken from particularly noteworthy victims, and including such items as skulls, heads, and enemy weapons. They do not take these trophies for any ritual purpose but rather for the tally of the Death-Speakers after the battle. They are then promptly discarded after serving their purpose unless judged to be particularly significant, in which case they are preserved as relics, often adorning the Space Marine's armour or wargear for a time.
The Executioners' spiritual beliefs have also been called into question, but have endured since before the rise of the Adeptus Ministorum. These beliefs primarily take the form of animism and ancestor worship, and while they ascribe to the worship of the divine God-Emperor, the Executioners have little use for the Ecclesiarchy and its trappings and "petty" superstitions, save for as a useful tool of social control to bind together the scattered multitudes of the Imperium.
- Lord Speaker of the Dead Thulsa Kane - The one-eyed Thulsa Kane is the current Reclusiarch (High Chaplain) of the Executioners, a role of singular importance within the Chapter which also carries with it the titles of "High Mortiurge" (or supreme-judge) and "Lord Speaker of the Dead," responsible for recording the deeds of the Executioners in battle and overseeing all of the Chapter's other Death-Speakers (Chaplains). During the lamentable conflict known as the Badab War (904-911.M41), Thulsa Kane led a force of Executioners on behalf of High Executioner Arkash Hakkon, to honour a millennia-old blood-debt to the Astral Claws. During the war, the Executioners steadfastly refused to operate under the direct control of the Tyrant of Badab, Lufgt Huron, operating only as the Astral Claws' uneasy allies and never as subordinates. This resulted in much ire within the ranks of the Secessionists during the war. The Chapter had a tendency to leave survivors of their attacks behind once their military objectives were met, even allowing the surrender of defeated foes with honour. This incensed Lugft Huron to no end. The Executioners eventually turned on the Astral Claws after the bloody events known as the Red Hour that occurred during the surrender of the Salamanders' Battle-Barge Pyre of Glory. The Executioners then became a rogue element, conducting their own private war with their former allies until they negotiated a surrender to the Loyalist forces and a withdrawal from the war zone in 911.M41. Thanks in no small part to the astute leadership of Thulsa Kane, of all those Chapters that were caught up in the Secessionist cause, the Executioners Chapter emerged from the conflict the least scathed and the least tainted. They had fought honourably and had lived and died by their oaths.
- Imperial Armour Volume Nine - The Badab War - Part One, pp. 24, 26, 40-41, 50, 51, 56, 119, 127
- Imperial Armour Volume Ten - The Badab War - Part Two, pp.10, 19, 30, 42, 44, 46, 54, 57, 59-61, 78, 84-93, 99, 109, 171, 175