A Blood Breed is a powerful creature from the Alterworld. Blood Breeds are some of the strongest antagonists in the series, able to give Libra considerable trouble in battle. In contrast to the average creature from the Alterworld, Blood Breeds are quite savage and bloodthirsty.
An upper-class subset called the Elder Blood Breeds also exist, which are generally more dangerous than the average Blood Breed. Originally thought by Libra to only number thirteen, Leonardo Watch's 'All-Seeing Eyes of the Gods' showed that the true number of Elder Blood Breeds was far more numerous.
Blood Breeds posses immense strength, speed, and destructive capacity, as well as an identifiable crimson aura. Two Blood Breeds shown thus far have been able to manipulate their blood into objects to attack and turn living beings into obedient ghouls. Blood Breeds have no reflection and are invisible to optical sensors such as cameras, although the 'All-Seeing Eyes of the Gods' are capable of detecting a Blood Breed because of their unique red aura even through these devices, and are able to see its true name if its heart is present in the relevant body.
Blood Breeds are also capable of regeneration; Elder Blood Breeds are even more skilled in that regard and may even be able to control parts of their body that have been split off from the whole: Girika was able to regenerate from the combined attacks of Steven A. Starphase and K.K. casually even after K.K.'s shot took off a significant portion of her head. Herlelle was fighting Raju Jugei Shizuyoshi with his lower body alone, and even that lower body was able to resist the latter's conjured fire storm for some time.
Even then, this did not yield in his end, as it encased itself in a Zhen Tai Dan (Chinese for "true womb egg"), a multi-eyed egg that defends the Blood Breed or its significant body parts and attacks those that get close enough to it while the Blood Breed regenerates within the egg. A tentacle from the Zhen Tai Dan of Herlelle's lower body was able to casually deflect bullets from a semi-automatic gun held by an armored police officer, and then tear apart the armored arm holding the gun, and even attack Zapp before he was able to conjure up his Blade 1: Homuramaru. Successfully destroying the eyes on the Zhen Tai Dan appears to make it non-hostile to stimulus, making it possible to relocate it elsewhere.
It is implied that it is possible to kill Blood Breeds, as with Raju's apparent track record of hunting them down without the ability to seal them. However, many of them have such fast regeneration that it seems to be the safer course of action, now that Libra has access to Leo's 'All-Seeing Eyes of the Gods.'
- Count Urthrchika (Oneshot Only).
- Valsh Rozzo Valctovoel Girika
- Tonio Andretti is a lower-class Blood Breed, having become one not long after Girika's intervention. Due to his relatively fresh vampirism, he is insufficient to combat a squad of armored police officers alone, requiring his mistress's help to do so. He attempts to intervene after Klaus leaps out of the subway to attack the pair, but is quickly crushed by Klaus's attack. (In the Manga, he is seen later recovering from this, despite the considerable amount of damage it did to him.)
- Herlelle Lucando Lozo Thietkaua gi Murmhavat
- Zamedle Lolow Zeaze Nazamsandriga is the Blood Breed that attacked Bradbury General Hospital.
- Alan Foster is raising a human child. Both leave the city after Alan's true identity is discovered by K.K.
- Ardamachael Zi Zirlahia Or Salzmailolos is a beast-like Blood Breed that went berserk in the city the day Michella Watch and Toby McLachlan arrived to Hellsalem's Lot.
- An unnamed Blood Breed appeared as a blood construct that exploded from Ozmaldo after his fight with Klaus Von Reinherz. This Blood Breed was able to effortlessly throw Klaus into the wall of the cage the two had fought in. The Blood Breed spared Klaus and was not fought after.
- The Tycoon Brothers,Maximilian and Yngwie. Two Blood Breed Mercenaries that are notoriously known in Hellsalem's Lot as being one of the most powerful bodyguards available. Accordingly they possess an undefeated track record where every single person or being that battled against them were killed.
- A Blood Breed is considered equivalent to our world's mythologized vampires.