Hurley plays chess with the spirit of Mr. Eko ("There's No Place Like Home, Part 2")
Mediumship is the ability to communicate with the dead. Mediumship is prominently exhibited in Miles Straume and Hurley Reyes (though through different methods), though other characters have occasionally been shown to see and communicate with apparitions of the dead.
Young Miles exhibits mediumship ("Some Like It Hoth")
Miles Straume exhibited his ability as a medium for the first time as a boy, when he heard the voice of Mr. Vonner calling from inside a closed apartment. Going inside, Miles discovered that Mr. Vonner was dead, though he could still hear Vonner's voice calling for his wife. ("Some Like It Hoth")
Though Miles was able to focus and use his ability, he remained unaware of its source. He eventually capitalized off of his ability by becoming a spiritualist, and began contacting people's deceased loved ones for large sums of money. One such case was that of a murdered drug dealer whose grandmother contacted Miles when the spirit of her deceased grandson would not leave the house. Miles then entered the boy's room, turned on his ghostbuster device, and spoke to the boy's spirit, finding out the location of a hidden stash of money before telling the spirit that it could "go now." ("Confirmed Dead")
Miles communicates with the spirit of Felix ("Some Like It Hoth")
Another case involved Russell Gray, the son of Howard Gray, who had been killed in an automobile accident. His father contacted Miles in an effort to make sure that his dead son was aware of his love, though Miles was unable to make contact with Russell's spirit due to the fact that the body had been cremated and the ashes spread. Miles instead lied, telling Gray that he had been able to contact the boy, in order to keep the large fee which he had just collected. ("Some Like It Hoth")
After the completion of the Gray case, Miles was met by Naomi Dorrit, who offered him a job interview at a nearby restaurant. Miles agreed, and was taken to the body of Felix and asked to find out all he could. Miles discerned that the body was that of a messenger who had been taking several documents regarding the faked Oceanic Flight 815 wreckage to Charles Widmore. Satisfied that Miles' ability as a medium was legitimate, Naomi offered him $1.6 million to come to the Island aboard the Kahana, to which Miles readily agreed. Having gained such a large sum of money, he returned to Howard Gray and gave him a refund, admitting that he lied. ("Some Like It Hoth") When Miles was shown Naomi's body, he was seen to be whispering something. What she told him, if anything, is unknown. ("Confirmed Dead")
Miles discovers the bodies of Danielle and Karl ("Something Nice Back Home")
Several days after his arrival on the Island, Miles was traveling with Sawyer and Claire when he began hearing the voices of Danielle and Karl, who had been killed by the mercenary team only a few hours before. After brushing aside a few leaves, Miles uncovered the corpses of Danielle and Karl shallowly buried in the mud. ("Something Nice Back Home")
Miles listens to the spirit of Alvarez ("Some Like It Hoth")
After flashing through time to 1954, Miles informed Daniel that they had walked over a grave that had been dug less than a month ago. Miles was able to determine that four U.S. soldiers had been buried there - three had been shot, the fourth had died of radiation poisoning. Daniel showed himself to be familiar with Miles' ability, as he enquired whether Miles could use it to discern the year they had arrived in. ("Jughead")
Miles' ability was not known to have been used again until three years later, after the flashes had placed him in 1977, where he began working for the DHARMA Initiative in security. On Horace's orders, Miles delivered a body bag to Radzinsky, who in turn placed Alvarez's corpse inside the body bag, telling Miles that Alvarez had fallen into a ditch. Miles, skeptical of Radzinsky's claims due to the nature of Alvarez's wounds, waited until Radzinsky had gone to invoke the spirit of Alvarez, whom he discovered had died due to his fillings being ripped through his head due to the electromagnetic properties of the area he had been working out (which was at that time being developed into the Swan).
Hurley and Miles discuss their abilities ("Some Like It Hoth")
Hurley later accompanied Miles in the DHARMA bus on its way to deliver the body to Pierre Chang at the Orchid. Hurley, after finding the body, questioned Miles about it. When Miles revealed that he knew what happened to the body, Hurley easily accepted the fact that Miles was a medium, telling Miles that he was could talk to dead people as well, and sometimes played chess with them. Though Miles argued that his powers did not work in the manner Hurley described, Hurley wrote this off as Miles being jealous because Hurley's powers "were better" than Miles'. ("Some Like It Hoth")
- In a deleted scene from "The Economist", Miles uses his ability to determine that the sonic fence was off. However, since this scene was deleted, the canonicity of this is disputed.
Hurley speaks to a deceased Charlie ("The Beginning of the End")
Hurley, a man who had once been sent to a mental institute for seeing an imaginary friend, first began seeing dead people after his escape from the Island. It is unknown whether these apparitions are real or imagined by Hurley. He first saw the corporeal manifestation of his dead friend Charlie in a convenience store. Hurley became so scared of this apparition that he fled in his Camaro, engaging in a high speed chase that ended with his arrest. While in an interrogation room, Charlie once again appeared, sending Hurley into a state of panic. He was then admitted once again to the mental health institute, where he was once again visited by a corporeal manifestation of Charlie (also seen by Lewis), who tried to convince Hurley to return to the Island. However, Hurley would not listen, and instead counted to five, causing Charlie to disappear. ("The Beginning of the End")
Charlie continued to visit Hurley, however, even forewarning Hurley of Jack's visit. Charlie's appearances caused Hurley to begin questioning his own sanity, and he began to believe that the survivors were all dead, and that they were living in an afterlife. ("Something Nice Back Home")
Hurley is visited by the ghost of Ana Lucia ("The Lie")
Hurley had other visitors during his time at the Institute. On the night that Sayid came to break Hurley out, Hurley had been engaged in a chess game with the late Mr. Eko. ("There's No Place Like Home, Part 2")
After a failed escape to a safe house, Sayid was knocked unconscious by several darts. Hurley began driving, and at one point swerved erratically. Sirens flared behind him, and he was pulled over by a police car, which was revealed to have been driven by Ana Lucia Cortez, who warned him to be more careful and less conspicuous. ("The Lie")
After the Reset, Hurley was visited by Jacob in the jungle. Jacob told him to go to the Temple to save Sayid's life. He also told him to bring the Guitar case with him, that Jacob gave him before the Ajira Flight 316 crash. Jacob told Hurley that Jin couldn't see him because he was murdered an hour ago. Shortly after that Jin came to Hurley and suddenly Jacob dissapeared. ("LA X, Part 1")
The Man in Black.
As a boy in Classical Roman times the Man in Black was told he was special by his mother. He later saw the ghost of Claudia, his birth mother, who lead him to the truth of his people, and turned him against his adopted mother, who had kidnapped him. In 2007, he can see an apparition of Jacob as he appeared when he was 13. This ability to see Jacob seems to be limited to him and other Candidates.
Several occurrences of people seeing the dead are his handiwork because as the Smoke Monster he can assume the likeness of the dead. This probably requires a body, though he doesn't possess them (and he no longer has his original). He eventually assumes the identity of John Locke as part of a longstanding an elaborate plan to leave the Island. Ilana claimed he was stuck like that. In the past he has appeared as Yemi to Mr. Eko, a smoky Alex to Ben, and claims to have appeared as Christian Shephard to Jack. However, as some of those occurrences appeared in places the Man in Black can't travel to (such as across water and off the Island) it is unlikely to be true every case.
Christian appears to Locke ("This Place Is Death")
- Christian Shephard's body was aboard Oceanic Flight 815 when it crashed, and his body went missing after the crash, though his empty coffin was found. Christian then began appearing to the survivors of the crash, though first to his son, Jack Shephard. ("White Rabbit") He later appeared to his daughter, Claire Littleton, and took her with him to Jacob's cabin. ("Something Nice Back Home") He has appeared to John Locke on multiple occasions ("Cabin Fever") ("This Place Is Death"), and also appeared to Michael shortly before Michael was killed in the Kahana's explosion. ("There's No Place Like Home, Part 2") He later appeared to Sun and Frank in 2007. ("Namaste")
- Several other dead people on the Island, including Yemi and Ana Lucia, appeared to Eko in visions and dreams, and once in reality. ("The Cost of Living")
- At one point, Locke sees the spirit of Horace Goodspeed, who had died in the Purge in 1992, in a cyclical motion, chopping wood. Horace speaks to Locke about the cabin, and gives Locke clues on where to go next. ("Cabin Fever")
- Locke was guided by Boone in a vision quest. ("Further Instructions")
- A young Ben saw his mother on the Island at least twice, despite her being dead since he was a baby. They also interacted. ("The Man Behind the Curtain")
- Michael has brief vision of Libby both off the Island and on the freighter, although these may have been brought on due to his guilt over her murder. ("Meet Kevin Johnson")
- Dogen later reveals that the Monster could only appear as the deceased. ("Sundown")
- Richard Malkin is a self-professed psychic in Australia whom Claire visited several times while pregnant. It is unknown whether he is truthful, because he never wants to take money from Claire. ("Raised by Another").