Polar bears were brought to the Island by the DHARMA Initiative, who kept them in cages at the Hydra station, on Hydra Island. (The World of the Others) According to Pierre Chang, because polar bears possess keen memory and adaptability instincts, they were prime candidates for studies in electromagnetic research. After training at the Hydra and solving the cage fish biscuit puzzles, the bears were fitted with a tracking collar, tranquilized, and taken to the Orchid where they were put in the familiar cold climate of the Frozen wheel chamber to push the wheel and be transported through space time. (The New Man in Charge) Some of the polar bears survived the Purge, after which they were freed from their cages and swam to the main Island. (Access Granted) After the crash of Oceanic Flight 815 in 2004, survivors of the crash occasionally encountered and were threatened by the bears. Charlotte Lewis discovered the skeleton and tracking collar of one of the experimented polar bears in Tunisia, where the Exit was located, that same year.
On the Island
- Sawyer, Kate, Boone, Shannon, Charlie, and Sayid were attacked by a polar bear in the jungle, which Sawyer then shot and killed. ("Pilot, Part 2")
- Walt was reading Hurley's comic book, which featured a polar bear. ("Pilot, Part 2")
- After being captured by Danielle Rousseau, Sayid heard a roar unlike that of the Monster outside in the jungle. When he asked what it was, Rousseau replied, "If we are lucky, it's one of the bears." ("Solitary")
- Walt was later attacked by a polar bear in the jungle. He hid inside a Banyan tree while the polar bear rammed at him. During this encounter, one can allegedly hear the polar bear say "Walter" as it swiped at the tree. ("Special")
- Pierre Chang read a book with a polar bear on the cover to 3 month old Miles Straume . ("Some Like It Hoth")
- Two polar bears appeared fighting on an ice floe in the Swan Orientation film. ("Orientation")
- The Latin name for "polar bear", Ursus maritimus, was mentioned on the blast door map, implying that the bears were used during experiments on the Island. ("Lockdown")
STATED GOAL, REPATRIATION ACCELERATED DE-TERRITORIALIZATION OF URSUS MARITIMUS THROUGH GENE THERAPY AND EXTREME CLIMATE CHANGE
- While chasing Dave, Hurley ran into Charlie and Mr. Eko and asked, "Did either of you see a guy run through here -- in a bathrobe, with a coconut?", to which Charlie replied, "No, but I did see a polar bear on roller blades with a mango." ("Dave")
- Tom said one of the cages at the Hydra was formerly used to house bears. ("A Tale of Two Cities")
- An attacking polar bear briefly appeared as a flash between the end of Locke's dream and him running out of the sweat lodge. Later, as a result of what he learned in the dream, Locke saved Mr. Eko from a polar bear in its cave. ("Further Instructions")
- A tuft of polar bear fur was discovered by Locke and Charlie. ("Further Instructions")
- Charlie told Locke that he used to get high and watch nature programs on the "Beeb" (BBC), where he learned that polar bears are very clever and "are like the Einsteins of the bear community." ("Further Instructions")
- When Phil caught Jerry and Rosie dancing and flirting in the DHARMA security room, Phil said that Rosie shouldn't be there, because it was their watch. Jerry joked that the worst thing that could happen would be the polar bears figuring a way out of their cages. ("LaFleur")
- When Pierre Chang found out Hurley knew about the dead body in the back of the DHARMA van, he threatened to assign Hurley to a job "shoveling polar bear feces" if he told anyone. ("Some Like It Hoth")
- There was a Polar Bear skull in the makeshift crib in Claire's hut. ("Lighthouse")
- The purpose of the bears was explained in the Hydra Orientation film by Dr. Chang. ("The New Man in Charge")
Off the Island
- Michael gave Walt a stuffed polar bear in a flashback. ("Adrift")
- Hurley read a comic book featuring a polar bear on the cover while on-board Flight 815. ("Exodus, Part 2")
- A stuffed polar bear toy appeared in the gigantic crib in which Drive Shaft filmed their commercial, "You All Every Butties". ("Fire + Water")
- One of the patients in the Santa Rosa Mental Health Institute was seen holding a stuffed bear during a basketball game. ("Dave")
- A polar bear appeared in a painting in Charles Widmore's office. ("Flashes Before Your Eyes")
- Charlotte Lewis unearthed a polar bear skeleton wearing a leather collar bearing the Hydra logo in the Tunisian desert in 2004. ("Confirmed Dead") It is heavily suggested in the series that the bear arrived there as a result of DHARMA experiments being carried out at the Orchid ("There's No Place Like Home, Part 2")
- The writers chose a polar bear attack rather than a boar attack in "Pilot, Part 2" because J.J. Abrams wanted to hint early on at the Island's unique nature. He suggested a genetically-enhanced animal (an idea that eventually produced the hy-bird), but producer Sarah Caplan suggested that viewers could confuse that with the monster. According to Damon Lindelof, he and Abrams suggested, in unison, that "It should be a polar bear!"
- According to the Season 1 DVD featurette, "Welcome to Oahu", FX supervisor Kevin Blank wore "polar bear chaps" and ran through heavy brush in order to simulate the legs of the polar bear seen in "Pilot, Part 2".
- Originally, director J.J. Abrams had been vehemently opposed to using a CGI polar bear on the show. The first version had a stuffed prop bear shot out of an air cannon towards Sawyer as he pretended to shoot at it. This version was shown on the pre-broadcast commercial before the pilot aired. Someone posted a freeze-frame capture of this online, which according to J.J., looked "laughable and ridiculous". He conceded to giving the CGI version, which he and the production team liked much better, a try. This was the version that ended up in the broadcast airing of "Pilot, Part 2". J.J. remarked that he was surprised people would analyze the show in such detail. The two versions can be seen below for comparison.
- Issue 11, "The Lost Shephard", of Lost: The Official Magazine had an article on polar bear production for "Further Instructions", showing images of Jonathan Arthur in his polar bear costume for the episode. It shows how the polar bear scenes were made.
- Damon Lindelof and Carlton Cuse suggest that fans curious about Charlotte's discovery of a polar bear skeleton in Tunisia watch the Orchid video and further draw a link between the bear and the bunny in the video. (Official Lost Podcast/February 19, 2008)
- Knowledge of the presence of polar bears on the Island has been used to demonstrate that the survivors did not always share knowledge.
- A band called You All, Everybody (a Lost tribute band) wrote and released a song about the polar bears in September 2006.
- The book Laughter in the Dark makes reference to polar bears in Hawaii. (Literary works)
- Polar bears are excellent swimmers that have been known to swim as far as 200 miles 
- The polar bear may be a reference to ironic process theory. From Wikipedia, a classic example is Fyodor Dostoevsky's quote from Winter notes on summer impressions: “Try to pose for yourself this task: not to think of a polar bear, and you will see that the cursed thing will come to mind every minute.” 
- The well-known "white bear" psychological experiments were performed by Wegner. These experiments, wherein the subject was asked to speak randomly into a tape recorder but was told "not to think of a white bear", resulted in compelling findings about attempts to suppress strange or unpleasant thoughts. Trying to avoid thoughts of the bear, most subjects mentioned a white bear very frequently in their taped meanderings. Called "ironic process theory," this finding is thought to prove that attempting to suppress a mental image only makes it occur more frequently.
- For fan theories about these unanswered questions, see: Polar bears/Theories
- How did the polar bears escape their cages?
- How many polar bears remain on the Island?
- Grantland: 'I Pretty Much Wanted to Die’ Alan Sepinwall, 11/26/2012