History of 21 May
- 1991 – In Madras, India, the former prime minister, Rajiv Gandhi was killed by a bouquet of flowers that contained a bomb.
- 1998 – An expelled student, Kipland Kinkel, in Springfield, OR, killed 2 people and wounded 25 others with a semi-automatic rifle. Police also discovered that the boy had killed his parents before the rampage.
- 1998 – Microsoft and Sega announced that they are collaborating on a home video game system.
- 1998 – In Miami, FL, five abortion clinics were hit by an butyric acid-attacker.
- 2001 – French Taubira law is enacted, officially recognizing the Atlantic slave trade and slavery as crimes against humanity.
- 2003 – The 6.8 Mw Boumerdès earthquake shakes northern Algeria with a maximum Mercalli intensity of X (Extreme). More than 2,200 people were killed and a moderate tsunami sank boats at the Balearic Islands.
- 2005 – The tallest roller coaster in the world, Kingda Ka opens at Six Flags Great Adventure in Jackson Township, New Jersey.
- 2006 – The Republic of Montenegro holds a referendum proposing independence from the State Union of Serbia and Montenegro; 55% of Montenegrins vote for independence.
- 2010 – JAXA, the Japan Aerospace Exploration Agency, launches the solar-sail spacecraft IKAROS aboard an H-IIA rocket. The vessel would make a Venus flyby late in the year.
- 2011 – Radio broadcaster Harold Camping predicted that the world would end on this date.
- 2012 – A bus accident near Himara, Albania kills 13 people and injures 21 others.
- 2012 – A suicide bombing kills more than 120 people in Sana’a, Yemen.
- 2017 – Ringling Bros. and Barnum & Bailey Circus performed their final show at Nassau Veterans Memorial Coliseum.
Celebrating Birthday Today
- 1981 – Craig Anderson, American ice hockey player
- 1981 – Edson Buddle, American soccer player
- 1981 – Josh Hamilton, American baseball player
- 1981 – Maximilian Mutzke, German singer-songwriter
- 1981 – Anna Rogowska, Polish pole vaulter
- 1983 – Līga Dekmeijere, a Latvian tennis player
- 1983 – Deidson Araújo Maia, Brazilian footballer
- 1983 – Kaori Shimizu, Japanese voice actress, and singer
- 1984 – Brandon Fields, American football player
- 1984 – Sara Goller, German volleyball player
- 1984 – Syamsul Yusof, Malaysian actor, film director, scriptwriter, film producer, rapper and singer
- 1985 – Mutya Buena, English singer-songwriter
- 1985 – Alison Carroll, English gymnast, model, and actress
- 1985 – Mark Cavendish, Manx cyclist
- 1985 – Alexander Dale Oen, Norwegian swimmer (d. 2012)
- 1985 – Isa Guha, English cricketer
- 1985 – Lucie Hradecká, Czech tennis player
- 1985 – Kano, English rapper, producer, and actor
- 1985 – Dušan Kuciak, Slovak footballer
- 1985 – Heath L’Estrange, Australian rugby league player
- 1985 – Andrew Miller, American baseball player
- 1986 – Mario Mandžukić, Croatian footballer
- 1986 – Myra, American singer and actress
- 1986 – Eder Sánchez, Mexican race walker
- 1986 – Park Sojin, South Korean singer-songwriter and dancer
- 1986 – Greg Stewart, Canadian ice hockey player
- 1987 – Beau Falloon, Australian rugby league player
- 1988 – Claire Cashmore, English Paralympic swimmer
- 1988 – Park Gyu-ri, South Korean singer
- 1988 – Jonny Howson, English footballer
- 1988 – Kaire Leibak, Estonian triple jumper
- 1989 – Emily Robins, New Zealand actress and singer
- 1989 – Hal Robson-Kanu, English footballer
- 1990 – Kierre Beckles, Barbadian athlete
- 1990 – Rene Krhin, Slovenian footballer
- 1991 – Guilherme, Brazilian footballer
- 1992 – Hutch Dano, American actor
- 1992 – Lisa Evans, Scottish footballer
- 1992 – Philipp Grüneberg, German footballer
- 1992 – Olivia Olson, American singer and actress
- 1993 – Grete Gaim, Estonian biathlete
- 1993 – Luke Garbutt, English footballer
- 1994 – Tom Daley, English diver
- 1995 – Katharina Andresen, Norwegian heiress and equestrian
- 1995 – Diego Loyzaga, Filipino actor
- 1996 – Josh Allen, American footballer
- 1996 – Indy de Vroome, Dutch tennis player
- 1996 – Karen Khachanov, Russian tennis player
- 1997 – Ivan De Santis, Italian footballer
- 1997 – Sisca Folkertsma, Dutch footballer
- 1997 – Viktoria Petryk, Ukrainian singer-songwriter