RMS Titanic was a British passenger liner, operated by the White Star Line, which sank in the North Atlantic Ocean on 15 April 1912 after striking an iceberg during her maiden voyage from Southampton, UK, to New York City. Of the estimated 2,224 passengers and crew aboard, more than 1,500 died, which made the sinking possibly one of the deadliest for a single ship up to that time. It remains to this day the deadliest peacetime sinking of a superliner or cruise ship. The disaster drew much public attention, provided foundational material for the disaster film genre, and has inspired many artistic works.

RMS Titanic was the largest ship afloat at the time she entered service and the second of three Olympic-class ocean liners operated by the White Star Line. She was built by the Harland and Wolff shipyard in Belfast. Thomas Andrews, who was the chief naval architect of the shipyard at that time, died in the disaster.Titanic was under the command of Captain Edward Smith, who went down with the ship. The ocean liner carried some of the wealthiest people in the world, as well as hundreds of emigrants from Great Britain and Ireland, Scandinavia and elsewhere throughout Europe, who were seeking a new life in the United States. The first-class accommodation was designed to be the pinnacle of comfort and luxury, with a gymnasium, swimming pool, libraries, high-class restaurants, and opulent cabins. A high-powered radiotelegraph transmitter was available for sending passenger "marconigrams" and for the ship's operational use. The Titanic had advanced safety features, such as watertight compartments and remotely activated watertight doors. The ship was equipped with 16 lifeboat davits, each of which were capable of lowering three lifeboats, for a total of 48 boats; the Titanic carried only 20 lifeboats, four of which were collapsible and proved hard to launch while the ship was sinking. Together, the 20 lifeboats were capable of holding 1,178 people—which was only about half the number of passengers on board, and only one-third of the number of passengers that the ship could have carried at full capacity (this was consistent with the maritime safety regulations of the era). In addition, when the ship sank, many of the lifeboats that had been lowered were only about half full.

Titanic had departed from Southampton on 10 April 1912, then stopped at Cherbourg, France, and Queenstown (now Cobh), Ireland, before heading west towards New York. On 14 April, four days into the crossing and about 375 miles (600 km) south of Newfoundland, she hit an iceberg at 11:40 pm ship's time. The collision caused the hull plates to buckle inwards along her starboard (right) side and laid five of her sixteen watertight compartments open to the sea; she had been designed to survive the flooding of up to four compartments. Some passengers and crew members were evacuated in lifeboats. A disproportionate number of men were left aboard because of a "women and children first" protocol for loading lifeboats, which was generally observed.At 2:20 am, the ship broke apart and foundered, with well over one thousand people still aboard. Just under two hours after Titanic sank, the Cunard liner RMS Carpathia arrived on the scene, and took on board an estimated 710 survivors.

The disaster was met with worldwide shock and outrage, both at the huge loss of life and at the regulatory and procedural failures that had led to it. Public inquiries in Britain and the United States led to major improvements in maritime safety. One of the most important results of the inquiries was the establishment in 1914 of the International Convention for the Safety of Life at Sea (SOLAS), which still governs maritime safety today. In addition, there was an effort to learn from the many missteps in wireless communications that had increased the number of fatalities, and as a result, several new wireless regulations were put in place around the world.The wreck of Titanic was discovered in 1985 by a Franco-American expedition sponsored by the United States Navy. The ship was split in two and is gradually disintegrating at a depth of 12,415 feet (2,069.2 fathoms; 3,784 m). Thousands of artefacts have been recovered and displayed at museums around the world. Titanic has become one of the most famous ships in history, depicted in numerous works of popular culture, including books, folk songs, films, exhibits, and memorials. Titanic is the second-largest ocean liner wreck in the world, only being surpassed by her sister ship HMHS Britannic; however, she is the largest sunk while in service as a liner, as Britannic was in use as a hospital ship at the time of her sinking. The final survivor of the sinking, Millvina Dean, aged two months at the time, died in 2009 at the age of 97; there are no survivors of the Titanic that are still alive today.