In parallel to its character development, episodes of Lost include a number of mysterious elements which have been ascribed to science fiction or supernatural phenomena. The creators of the series refer to these as part of the mythology of the series, and they form the basis of rampant fan speculation.
Among the show's mythological elements is a "monster" which appears to roam the island; a mysterious group of hostile inhabitants whom the survivors refer to as "The Others"; an organization called the "DHARMA Initiative" which has placed several research stations on the island; a sequence of numbers which have made frequent appearances in the lives of the characters, in both the past and present; and personal connections between the characters, of which they are often unaware.
| The Monster
The "monster" was the first piece of mythology introduced on the show. It first appears during the night after the crash when the survivors hear a loud, unidentifiable sound coming from the jungle and witness trees being torn down in the distance. The next day, Jack, Kate, and Charlie see the power of the monster first-hand when it rips the pilot from the cockpit and leaves his mangled body in a tree.
The Whispers are voices heard in the jungle. In Everybody Loves Hugo, Michael explained to Hurley that the the whispers were dead people stuck on The Island,who were unable to move on because of what they did when they were alive.Whispers are often heard during encounters between the survivors and The Others,as well as The Monster,. And it is heavily implied that the whispers have an agenda,and want to warn people about danger.
Prior to their arrival on the island, both major and minor characters had occasion to interact, often unknowingly, sometimes affecting each others' lives. These are revealed through characters' flashbacks, and are typically only obvious to viewers.
| The Others
"The Others" are mysterious inhabitants of the island whose presence predates the crash of Flight 815, as well as Danielle Rousseau's arrival. In addition to kidnapping Rousseau's daughter, Alex, as an infant, the Others have infiltrated the Flight 815 survivors' camps on at least two occasions, and are responsible for the deaths of at least two castaways and the unexplained disappearances of many others.
| The Numbers
The numbers 4, 8, 15, 16, 23 and 42 appear throughout the series, both in sequence and individually. They were broadcast from the Island's radio transmitter, and it was this message that drew Rousseau's expedition there. Although she later changes the message after the deaths of the rest of her team, the digits had also been heard by other people, eventually making their way to Hurley, who used them to win a lottery.
| The DHARMA Initiative
The DHARMA Initiative was established in 1970 by University of Michigan doctoral candidates Gerald and Karen DeGroot and financed through Alvar Hanso and his Hanso Foundation. It comprises a group of "scientists and free thinkers" who were brought together at a "large-scale communal research compound" to conduct research into meteorology, psychology, parapsychology, sociology, zoology, and electromagnetism.
There have been a number of instances in which the survivors encounter animals that are either not native to the island or have special attributes. Among the animals on the island are polar bears, wild boars, chickens, giant birds, tree frogs, horses, and a Yellow Labrador named Vincent.
On the Island, numerous characters experience auditory and visual hallucination-like phenomenon, including apparent visions and messages from deceased family members. Both Jack and Eko receive visitations from dead relatives whose bodies are present on the island; however, the dead bodies of Jack's father Christian Shephard and Eko's brother Yemi had disappeared. Kate's dead stepfather's spirit briefly invades Sawyer's body and tries to choke Kate.
Some castaways have expressed belief that they have been miraculously healed since the crash. Prior to his arrival, Locke was confined to a wheelchair, but he regained the use of his legs immediately after the crash; he tells Walt that a miracle happened to him. Rose had terminal cancer before the crash. She tells her husband Bernard that the illness has vanished since they have been on the island, causing Bernard to abandon all efforts to be rescued or escape.