Extremely Severe Cyclonic Storm Nargis (Burmese: နာဂစ်, Urdu: نرگس [ˈnərɡɪs]) was an extremely destructive and deadly tropical cyclone that caused the worst natural disaster in the recorded history of Myanmar during early May 2008. The cyclone made landfall in Myanmar on Friday, 2 May 2008, sending a storm surge 40 kilometres up the densely populated Irrawaddy delta, causing catastrophic destruction and at least 138,373 fatalities. The Labutta Township alone was reported to have 80,000 dead, with about 10,000 more deaths in Bogale. There were around 55,000 people missing and many other deaths were found in other towns and areas, although the Myanmar government's official death toll may have been under-reported, and there have been allegations that government officials stopped updating the death toll after 138,000 to minimise political fallout. The feared 'second wave' of fatalities from disease and lack of relief efforts never materialised. Damage was at $12 billion, making Nargis the costliest tropical cyclone on record in the North Indian Ocean at the time, before that record was broken by Cyclone Amphan in 2020.The first named storm of the 2008 North Indian Ocean cyclone season, Nargis developed on 27 April in the central area of Bay of Bengal. Initially, the storm tracked slowly northwestward, and encountering favourable conditions, it quickly strengthened. Dry air weakened the cyclone on 29 April, though after beginning a steady eastward motion, Nargis rapidly intensified to attain peak winds of at least 165 km/h (105 mph) on 2 May, according to IMD observations; the JTWC assessed peak winds of 215 km/h (135 mph), making it a weak Category 4 cyclone on the SSHWS. The cyclone moved ashore in the Ayeyarwady Division of Myanmar at peak intensity and, after passing near the major city of Yangon (Rangoon), the storm gradually weakened until dissipating near the border of Myanmar and Thailand.

Nargis is the deadliest named cyclone in the North Indian Ocean Basin, as well as the second-deadliest named cyclone of all time, behind Typhoon Nina of 1975. Including unnamed storms like the 1970 Bhola cyclone, Nargis is the fifth-deadliest cyclone of all time, but an uncertainty between the deaths caused by Nargis and those caused by other cyclones (like the 1991 Bangladesh cyclone), could put Nargis as fourth-deadliest or higher, because the exact death toll is uncertain. Nargis was the first tropical cyclone to strike the country since Cyclone Mala made landfall in 2006, which was slightly stronger, but had a significantly lower impact. According to reports, Indian authorities had warned Myanmar about the danger that Cyclone Nargis posed 48 hours before it hit the country's coast.

Relief efforts were slowed for political reasons as Myanmar's military rulers initially resisted large-scale international aid. US President George W. Bush said that an angry world should condemn the way Myanmar's military rulers were handling the aftermath of such a catastrophic cyclone. Myanmar's military junta finally accepted aid a few days after India's request was accepted.Hampering the relief efforts, only ten days after the cyclone, the 2008 Sichuan earthquake occurred nearby and measured 7.9 in magnitude, taking 87,476 lives and causing US$150 billion in damage in the process, making it the costliest disaster in Chinese history and third-costliest disaster ever known. Furthermore, some donated aid items were found to be available in the country's black market, and Myanmar's junta warned on 15 May that legal action would be taken against people who traded or hoarded international aid.