Though there is little known about him and his origins, eyewinesses have reported Jack having the following abilities.
Intelligence- Though the true measure of his intellectual capacity is unknown, Jack has demonstrated in the past that he is both sentient and intelligent as he is able to understand and communicate with humans to a degree. However he is incapable of speech and can only communicate by means of hand gestures and other non-vocal forms of communication. Because of his immortality, Jack has vast measures of knowledge and experience that he has learned through countless centuries.
Superhuman Abilities- Being inhuman, Jack has a number of superhuman abilities. Jack has been shown to be superhumanly strong as he has demonstrated by accomplishing various feats of superhuman strength, for example on one such encounter with a human, Jack was able to lift and throw a rock that even twenty men couldn’t move. Jack has also been shown capable of running at superhuman speeds, moving so fast that an afterimage is where he was previously standing. Other superhuman abilities that Jack has shown are agility and reflexes, these are shown when in one such encounter Jack was easily able to dodge the path of a bullet with relative ease. It has been said that Jack displays an uncanny awareness if someone mentions his name, it is unknown if he can actually hear his name being mentioned or that he is simply aware that it has been mentioned. However the only evidence of this was found in the form of a poem so this may be just a part of the creativity of the human mind rather than an actual ability however it is still worth being noted.
Phase- Jack has been shown capable of phasing through solid objects, this is prominently shown in his famous “Axeman” murders where he was able to enter the house without using the doors or windows. It is unknown if this was due to an ability to phase through solid objects or an ability to teleport (see teleportation).
Teleportation- Jack has been shown to have the ability to teleport from one area to another, though the exact range of this ability is unknown. Jack has used this to a great effect in attacking his victims as he prefers to take them by surprise. It is unknown if Jack’s ability to phase through solid objects is actually just his ability to teleport from an area (see Phase).
Haunting Abilities- Though it is unknown if Jack is in fact a spirit but what is known however is Jack has demonstrated several abilities that have the characteristics of ghosts. These abilities include the ability to manipulate the energies of devices in order to create words, the ability to mentally “speak” in the white noise frequency. Sadly he has only been shown in one case however so it is difficult to conclude the existence of such abilities as the video to which it was demonstrated on could likely have been a hoax, but the possibility of this however is unlikely.