The Icelandic Coast Guard (Icelandic: Landhelgisgæsla Íslands, Landhelgisgæslan or simply Gæslan) is the Icelandic defence service responsible for search and rescue, maritime safety and security surveillance, national defense, and law enforcement. The nautical division is based at the port of Reykjavík, as well as a smaller base at Siglufjörður. Its aeronautical division is based at Reykjavík Airport.

The Coast Guard is also responsible for the NATO area at Keflavík Airport and the Iceland Air Defence System, which conducts ground-based surveillance of Iceland's air space. It is also conducts hydrographic surveys and nautical charting.

Its origins can be traced to 1859, when the corvette Ørnen started patrolling Icelandic waters. In 1906, Iceland's first purposely built guard-ship, Islands Falk, began operation. Iceland's own defense of its territorial waters began around 1920 and the Icelandic Coast Guard was formally founded on 1 July 1926. The first cannon was put on the trawler Þór in 1924 and on 23 June 1926 the first ship built for the Coast Guard, named Óðinn, arrived in Iceland. Three years later, on 14 July 1929 the coastal defence ship Ægir was added to the Coast Guard fleet.

The Icelandic Coast Guard played its largest role during the fishing rights dispute known as the Cod Wars, between 1972 and 1976, when the Coast Guard ships would cut the trawl wires of British and West German trawlers, resulting in confrontations with Royal Navy warships and tugs from the British Ministry of Agriculture, Fisheries and Food (MAFF). The Icelandic Coast Guard goal was to enforce a disputed expansion of Iceland's exclusive economic zone. Engagements between Icelandic gunboats and British warships involving ramming became the tactic of choice during this conflict. At least 15 British frigates, five Icelandic patrol boats and one British supply ship were damaged by ramming between 1975 and 1976. In the end, Iceland achieved its overall ambition of expanding its exclusive fishery zone to 200 nautical miles (370 km) by June 1976.

The Icelandic Coast Guard's (ICG) primary mission as stipulated in Section 1 of Act on Icelandic Coast Guard is conduct search and rescue, maritime safety and security surveillance, and law enforcement inside the 200-nautical-mile (370 km; 230 mi)-wide economic zone. The Coast Guard operates Joint Rescue and Coordination Centre (JRCC) Iceland which is responsible for search and rescue of vessels and aircraft in Iceland's search and rescue region (SRR) according to International Aeronautical and Maritime Search and Rescue (IAMSAR) Manual. Additionally the ICG is in the charge of defusing naval mines, most of which were laid during the Second World War, and monitoring fisheries in international waters outside of the Icelandic economic zone in order to blacklist any vessel partaking in unregulated fishing and thus bar them from receiving services from any member of the North East Atlantic Fisheries Commission in order to make unregulated fishing unprofitable. The Icelandic Coast Guard also occasionally operates within Greenlandic and Faeroese waters, following a bilateral agreement with Denmark regarding mutual aid in security, rescue and defence matters.

The Coast Guard accomplishes these tasks with the use of offshore patrol vessels (OPV), helicopters, surveillance aircraft, satellites and a network of land based surface scanning radar.

The Icelandic Coast Guard is also in charge of the Iceland Air Defence System, which operates four ground-based AN-FPS(V)5 air surveillance radars and a control and command centre.

In the 1990s the Coast Guard started hosting exercises such as "Northern Challenge" which had military units from Norway, Denmark, Sweden and the United Kingdom, among others, participating along with the Icelandic Coast Guard. The Coast Guard has also taken part in peacekeeping operations on behalf of the Icelandic Crisis Response Unit, although while usually using their own rank insignia, uniforms and weapons.