Black Iron Tarkus is a mighty knight who helps you in Sen's Fortress. He might be one of the Berenike Knights who survive Sen's Fortress, judging by his heavy armor and location. But, he may be from a different order of knights altogether.
- The player must be in human form for Tarkus' soul sign to appear.
- Black Iron Tarkus is a very powerful ally. He can easily distract the Iron Golem and take a lot of damage if the player wishes to fight from a distance. He also makes it much easier to stagger the boss, allowing for a swift kill. Ultimately, he can even kill the Iron Golem alone, especially on first playthrough (if lucky, he can even kill the golem on NG+6).
- Be careful when leading Tarkus around Sen's Fortress if you don't take him immediately to the Iron Golem fog gate. If you take him below to help with the Heavy Knight, it's possible that he won't be able to make it back to help with the boss fight as he has trouble navigating the narrow pathways on the roof. If he continues to fall down while trying to follow you, eventually he'll die.
- A corpse, probably his, containing the Black Iron Set and the Black Iron Greatshield can be found near the large painting in Anor Londo.
- Tarkus means "wisdom" in Estonian.
- Black Iron Tarkus is likely a reference to the antagonist Knight Tarkus from the 1986 manga JoJo's Bizarre Adventure. Both Tarkuses are massive knights with enormous, seemingly unwieldy weapons and thick armor. The title "Black Iron" may also refer to Tarkus' companion, Black Knight Bruford. The way Black Iron Tarkus dies is also similar to how Tarkus from the manga falls off a cliff and into a barracks.