- "The Errant is surely the finest of Knights. A cannon of unsurpassed power, against which no heretic armour is proof. A blade fit to cut down the most monstrous beasts in honourable close-quarters combat. A fiery warrior spirit the equal of even the most bellicose pilot. Yes, give me a Knight Errant, and I shall deliver you victory."
- —Sir Tadwynne of House Boros
The Knight Errant Imperial Knight is a mainstay of many knightly houses. Of the varied types of Questoris-class Imperial Knight seen upon the battlefields of the late 41st Millennium, the Knight Errant is best known as a devastating, close-ranged killer -- a tank-hunter extraordinaire. Many an enemy vehicle has been quickly melted to no more than hissing piles of molten slag by the Thermal Cannon slung underneath a Knight Errant's mighty shoulder. Once a foe is sighted, a Knight Errant typically seeks to close the distance -- firing off hissing blasts from its Thermal Cannon as its great strides propel the walker rapidly forward. Thanks to their size, thick adamantium armour and directional Ion Shield, Knights Errant do not hesitate to charge straight into the teeth of the enemy's most potent weapons.
Knights Errant are best used as aggressive, mid-to-close-range assault platforms. Pounding into battle at the vanguard, these war engines excel at hunting enemy tanks, walkers and monstrous beasts, especially amidst the tangled terrain of cityscapes, jungles and the like. This is thanks in no small part to the hideously destructive capabilities of their traditional primary armaments: the Thermal Cannon and Reaper Chainsword.
Once amongst its foes, a lone Knight Errant can best an entire tank battalion, shooting and stabbing its way through the enemy formation to leave only twisted ruin and blackened hulls in its wake. The Knight Errant's close combat weapon -- either a Reaper Chainsword or Thunderstrike Gauntlet -- is perhaps more deadly still. When powered by the Knight's mighty servo-engines, either of these weapons can topple even the most monstrous xenos creature with a single strike. Fitted into the Knight Errant's armoured carapace is a Heavy Stubber to scythe down enemy infantry, and its armour-plated feet are more than capable of crushing units beneath its awesome weight.
Based on the same ancient Questoris-class chassis as the Knight Paladin armour, the Knight Errant mark armour mounts an imposing Thermal Cannon in place of a Rapid-Fire Battle Cannon. This terrifying weapon is more than capable of vaporising even the most resilient of armour plate in an instant. Most often employed to hunt down and destroy enemy super-heavy monstrous xenos creatures, Errant mark Knight armours are usually assigned to the more aggressive scions of the knightly houses, and in turn the Errant armours themselves often develop a belligerent anima (artificial intelligence). Few Errant armours carry the long lineage of many Knights Paladin, as only the most skilled survive for long, though such armours often carry with them a collection of battle honours that few others can match. Some of the oldest Errant armours, veterans of many lifetimes of battle, are so fractious of spirit and spiteful of temperament that only the most iron-willed of scions can master them, bending their bloody instincts to the service of the Household.
In the late 41st Millennium, the Knight Errant is a mainstay of many knightly houses. The strengths of the Knight suit are perfectly matched by the aggressive, charge-the-foe nature of its pilots. Knights Errant often spearhead attacks, and by a battle's end they will have smashed and carved their bloody way into the very thickest of the fighting. Even protected by their armour and Ion Shield, battle damage is common for such venerable engines of war. After each action, the hulking giants are literally crawling with Sacristans, for most knightly households uphold the tradition that post-battle a Knight should not be seen with so much as a single scratch upon its livery. The ancient machines are lovingly cared for, with attention paid to every armour plate and sacred unguents lavished upon every cog. No less scrutiny is spent ensuring that the Knight's personal heraldry is likewise maintained, for the symbols it incorporates proclaim everything that a Noble takes pride in, including his homeworld, House, oaths, rank and his most lauded battle honours.
As a battle begins, Knights Errant invariably choose to close with their foes, and any enemies not despatched by blasts from the deadly Thermal Cannon are quickly put to the test by the Knight Errant's Reaper Chainsword. It is a trial that few creatures or war engines, no matter how massive or well-armoured, can survive. The adamantine teeth of the Reaper blade can churn through ferrocrete bunkers or rip open a super-heavy battle tank. Some Knights Errant choose a Thunderstrike Gauntlet over the great blade, using the unmatched power of its grip to bludgeon foes to the ground, to crush the innards of living creatures, or to rip limbs from enemy Titans. Such is the awesome power of the Thunderstrike Gauntlet that tanks can even be flipped over or hurled aside to roll and crash amongst the Knight's foes. The extra carapace mounting allows Knights Errant to bear another weapon, including the anti-aircraft twin-linked Icarus Autocannon -- an addition often included by Tech-priests that expect to operate beneath enemy-controlled skies.
While all Knight Houses make use of the Knight Errant pattern armour, perhaps none are so feared as those that fight for Forge World Lucius. While unable to replicate the teleportation abilities bestowed upon the Titans of the Legio Astorum -- the legendary "Warp Runners" -- the Tech-priests have had some limited success in sending smaller units. During the defence of their world against Hive Fleet Leviathan, the robed leaders of Lucius succeeded in sending a phalanx of Onager Dunecrawlers directly into the midst of the foe. Continually working to improve the method, the Tech-priests found they were able to send larger and larger war machines into the fray. By the invasion's end, they concluded that sending a Knight Errant deep into enemy lines provided maximum disruption, the massive war machine able to instantly destroy swathes of Tyranid creatures. Naturally, all the Knights Errant seconded or allied to Lucius wished for the distinctive honour of leading the slaughter. Although anathema to the practical and logic-minded Tech-priests, the varied Knight Houses began what is now known as the "Lucian Contest" -- an honour duel fought by Nobles to earn the right to be teleported directly into battle.
- 1 Knight Errant
- Heavy Stubber
- Thermal Cannon
- Reaper Chainsword
- Ion Shield
- Throne Mechanicum
- Titanic Feet - The weight of the Knight alone is enough for to crush enemy units beneath its behemoth tread.
- Thunderstrike Gauntlet (As replacement for Reaper Chainsword)
- Meltagun (As replacement for Heavy Stubber)
- Ironstorm Missile Pod
- Twin-linked Icarus Autocannon
- Stormspear Rocket Pod
- Bio-corrosive Rounds for Heavy Stubber (31st Millennium Only) - Replaces the Knight's Heavy Stubber's standard ammunition for Bio-corrosive tipped rounds. These rounds are capable of eating through both flesh and armour.
- Occular Augmetics (31st Millennium Only) - An upgrade to the Knight's Occular sensors enabling a far greater degree of visual input during low-light conditions, such as night fighting.
- Codex: Adeptus Mechanicus (8th Edition), pp. 57, 84
- Codex: Imperial Knights (8th Edition), pp. 60, 94
- Codex: Imperial Knights (7th Edition) (Digital Edition), pp. 9, 11, 20, 26, 31, 38-40, 42-43, 46, 49, 55-56, 58, 60, 67, 71, 74-76, 79-80, 83-84, 88-89, 93, 96, 99, 102
- Codex: Imperial Knights (6th Edition) (Digital Edition), pp. 3, 9-10, 135-136
- The Horus Heresy - Book Four: Conquest (Forge World Series) by Alan Bligh, pg. 302
- The Imperial Knight Companion (6th Edition), pp. 17, 24-25, 28-29, 31, 36, 42, 48, 52, 56, 62, 64-66, 70, 72, 78-79, 86, 88, 92, 94, 98, 124, 126-129, 138, 142
- White Dwarf Weekly 66 (May 02, 2015), "Regiments of Renown," pg. 78
- White Dwarf Weekly 23 (July 05, 2014), "Knights of the Household," "Designer Notes," pp. 48, 50, 59-60
- White Dwarf Weekly 7 (March 15, 2014), "Joining the Crusade," "The Rules - Apocalypse Datasheet," pp. 19, 22, 50-51, 59-60
- White Dwarf Weekly 5 (March 01, 2014), "Imperial Knights," "The Imperial Knights Companion," "House and Heraldry," "Creating Your Own Freeblade," "Hold the Line!," "Paint Splatter," pp. 3, 10, 19, 23, 28, 30, 32, 40, 44, 50, 64
- White Dwarf Weekly 4 (February 22, 2014), "Imperial Knight," "The Rules - Imperial Knights," pp. 9, 56-58