Here are a few famous castaways (of the non-Gilligan variety).
1. Alexander Selkirk. We'll start with the original. In October 1704, Selkirk was serving as a sailing master on the St. George. When the ship stopped at the archipelago of Juan Fernandez, Selkirk tried to convince most of the crew to stay on the island with him, saying that the ship was not seaworthy and the captain wasn't leading well. In the end, he was the only one who stayed on the island, and he figured that another ship would be along soon enough and he would catch a ride with them. He figured wrong: it would be nearly four and a half years before a friendly ship crossed his path (two Spanish ships showed up before then, but he didn't trust them). In the meantime, he fended for himself just fine, eating feral goats, wild turnips and black pepper berries. He even built a couple of huts for shelter. These days, the island he lived on has been renamed Robinson Crusoe, and a nearby island that he likely never set foot upon has been christened Alexander Selkirk.
2. Leendert Hasenbosch. Unlike our first two castaways, Hasenbosch was not so successful as a castaway. This Dutchman was abandoned on Ascension Island in the South Atlantic in 1725 as punishment for sodomy. His crew didn't just leave him for dead, though—a diary left behind by the man indicated that he began his stay with a tent, seeds, a month's worth of water, books, writing materials and even extra clothes. The problem? The island apparently had no fresh water source. After his month's supply ran out, Hasenbosch took to drinking turtle blood and his own urine to try to stay hydrated. He likely died after about six months; British sailors discovered his abandoned tent and diary in January, 1726. Hasenbosch didn't need to die, though: there are actually two sources of fresh water on the island, one of which actually allowed the entire crew of the HMS Roebuck to survive a shipwreck for two months in the early 1700s.
3. Marguerite de La Rocque. Marguerite was sailing to the New World with a relative in 1542—the exact nature of this relative is unknown, with varying sources claiming it was her brother, cousin or uncle—and began sleeping with a man on the ship. Her brother/uncle/cousin was displeased and turned them both out on the "Isle of Demons." It's said that he would have financially benefited from her death, so perhaps her relative's reasoning wasn't all about morality. Marguerite's maid-servant was also dumped on the island. We aren't exactly sure how long Marguerite was on the island, but it was long enough to get pregnant and have the baby, then watch the baby die from malnutrition. Her lover and her maid-servant also died, leaving Marguerite to hunt wild game to stay alive - yeah, Kate Austen's got nothing on this chick. Eventually, a group of fishermen found Marguerite and brought her back, where she relayed her captivating tale to the Queen of Navarre, which is how we know about it today. Historians are fairly sure that the "Isle of Demons" is the one we know today as Hospital or Harrington Island; Marguerite's Cave is a popular attraction on the island these days.
4. Ada Blackjack. You think being stranded on a tropical island is tough? Try being stranded in Siberia. That's what happened to Inuit Ada Blackjack in 1921. She accompanied a group of men who were sent to claim Siberia's Wrangel Island for Canada; Ada was meant to be their cook and seamstress. Things went bad quickly—rations ran out, hunting was terrible and one man was deathly ill - and in January 1923, three of the four men left to trek across the frozen sea back to the mainland to try to get help, leaving Ada and the ailing explorer, Lorne Knight, on the island. They were only gone for a couple of months when Knight died of scurvy, leaving Ada to fend for herself. And she did. For five months, Ada survived with nothing but a cat for companionship. She was rescued in August, 1923, and the three men who took out across the ice nine months earlier were never heard from again.
5. Narcisse Pelletier. I'm not sure I have the skills it would take to last on a desert island now, as an adult, let alone as a teenager. But Narcisse Pelletier did. He was only 14 when the ship he was serving on struck a reef in Papua New Guinea in 1858. When some of the crew members tried to get to nearby Rossel Island for water and supplies, they were attacked by its inhabitants. The crew members who managed to survive the attack jumped in a long boat and paddled the heck out of there. Almost two weeks later, the crew made it to an island, where they found fresh water to quench their thirst. Apparently wanting one less mouth to feed, the crew abandoned Pelletier on the island where three Aboriginal women found him. They ended up adopting him, giving him the new name "Amglo."
6. Otokichi. It's too bad Otokichi and Narcisse Pelletier never met, because they surely would have had a lot to talk about. Otokichi was also 14 when the rice transport ship he was on blew off course in 1832. It drifted for 14 months while the crew slowly ate away at their cargo. By the time the ship drifted ashore on Washington's Olympic Peninsula, only three of the 14 original crew members were still alive, including Otokichi. The men were found by the Makah Indian tribe and were enslaved before being handed over to the Hudson Bay Company.
7. Poon Lim. Here's a comparatively recent castaway—Poon Lim's tenure on a raft afloat in the South Atlantic occurred during WWII. He was working as a steward on a British ship that was torpedoed 750 miles east of the Amazon. As the ship exploded, Lim grabbed a life jacket and jumped off, making him the only survivor of his 54-man crew. As luck would have it, he floated for a couple of hours and then found a life raft that had floated away from the wreckage. It contained 40 liters of water, a small amount of food, flare guns and a few other supplies. For 133 days, Lim managed to stay alive by fishing from the raft. He was spotted by U.S. Navy planes and they dropped a marker buoy in the water so they could come back and rescue him, but sadly, a huge storm hit just after and Lim was lost again. Finally, on April 5, 1943, he hit land and was rescued by Brazilian fisherman.
8. Philip Ashton. After being captured by a band of pirates in 1722, this sailor escaped their clutches and hid in the jungle of Roatan Island in the Bay Islands of Honduras until they gave up looking for him and sailed on. For a while, Ashton's diet consisted of nothing but fruit, because he had escaped his captors with nothing but the clothes on his back. He had no weapons to kill animals with and apparently was unable to devise a way to fish. Lucky for him, he happened across another castaway. They were great friends for three days, until the unnamed man went out for food and never came back. He did, however, leave behind a great stash of gunpowder, knives and tobacco, which allowed Ashton to start killing tortoises and cooking them. He was rescued by a ship from New England shortly thereafter. Sound made up? You're not the only one who thinks so. When Ashton published his memoirs after getting back to the U.S. in 1725, everyone thought they were fiction - Robinson Crusoe had only been on bookshelves for a few years and everyone thought this was a similar adventure story.
9. Charles Barnard. In 1812, Barnard's ship rescued a British ship called Isabella, which had been wrecked off Eagle Island, part of the Falklands. While they were docked at Eagle Island, Barnard and a few of his crew decided that they would need more provisions since they were picking up this shipwrecked crew and went ashore to gather some things. Not ones to show gratitude, the crew of the Isabella took over Barnard's ship while he was out and left their rescuers to fend for themselves on Eagle Island. Luckily, they were rescued 18 months later.
10. Tom Neale. There are all of these people who were stranded on islands or boats and wanted nothing more than to get to civilization again, and then there's Tom Neale. Neale desperately wanted an island all to himself, and in October 1952, he got his chance. A boat passing by Suwarrow Island, a place uninhabited since WWII, agreed to drop him off there, along with two cats and as many supplies as he could carry. The people who had lived there before WWII had left behind chickens and pigs, so he ate the pigs and domesticated the chickens, planted a garden, built a hut and lived his happy island life. That is, until May of 1954, when he threw his back out. At least, he thought he did. He hitched a ride to Rarotonga, another one of the Cook Islands, and went to a hospital, where he was told it was just arthritis. He returned to Suwarrow in 1960 and lived similarly for another four years. His third and final stay on the island lasted from 1967 to 1977, when a yacht stopped at the island and found Neale quite ill. They took him to Rarotonga, where Neale discovered he had stomach cancer. He died eight months later.