Klaus Hargreeves

Klaus Hargreeves, originally designated as Number Four, is one of the forty-three children who were all born on the 12th hour of the first day of October 1989 to mothers without any previous signs of pregnancy. The baby was one of seven adopted by Sir Reginald Hargreeves with the intention of training them to save the world. Ranked by their individual usefulness, Klaus was Hargreeves' Number Four with the ability to speak to the dead. Klaus found himself transported to Dallas, February 11, 1960, when Five failed to avert the apocalypse. Klaus became the leader of a spiritual cult and despite the fame associated, he struggled more and more with his inner demons. He and Ben struggled with their relationship but began experimenting more with their combined abilities.

Klaus is a damaged, fragile man who covers his pain with self-deprecating humor and cynical hedonism; and has rebelled against his father by refusing to be the hero he wanted him to be. He plays into the role of an unreliable, unrepentant leech and drug addict, and as a result his opinion is often dismissed by his siblings. However, he is shown to have a deeper insight than assumed and has even shown to be a voice of reason to his family's impulsive decisions. At the same time, he seems to have a better, healthier mindset of his childhood. He acknowledges and accepts that his childhood was traumatic and moves forward without visibly dwelling on it too much. It is revealed that the primary reason for his addiction is because powers cause him to be plagued by horrific, frightening visions of dead people who constantly call out to him. The drugs and alcohol are the only things that are able to subdue his powers and make the visions stop. His loyalty to his siblings, especially Diego and Luther, is shown through his actions, though he does act like any sibling would by teasing and arguing with all six of the other Hargreeves children. He is deeply cynical and constantly making jokes to deal with his trauma, much to the annoyance of those around him.