Hun Sen (1979 - Now)
Hun Sen (born 5 August 1952)is the Prime Minister of Cambodia and leader of the Cambodian People's Party (CPP), which has governed Cambodia since the Vietnamese-backed overthrow of the Khmer Rouge in 1979. Since the restoration of multi-party democracy in 1993, the CPP has been in a coalition with the royalist Funcinpec party.
His full honorary title is Samdach Akaek Moha Sena Padei Decho Hun Sen (The title "Samdech" was attached to his name in 1993 by King Norodom Sihanouk, though this does not give him additional powers. He has a glass eye, the result of a wound sustained during the Khmer Rouge offensive against Phnom Penh in April 1975. Hun Sen is the second longest serving leader in Southeast Asia and is one of the longest serving prime ministers in the world, having been in power through various coalitions since 1985.
Hun Sen was born in Kampong Cham, and was the third child of six children to a peasant family. His father, Hun Neang, was a resident monk in a local Wat in Kampong Cham province before defrocking himself to join the French resistance and married Hun Sen's mother, Dee Yon in the 1940s. Hun Neang's paternal grandparents were wealthy landowners of Teochew Chinese heritage.Hun Neang inherited some of his family assets and led a relatively comfortable life, as they owned several hectares of land until a kidnapping incident forced their family to sell off much of their assets.Hun Sen left his family at the age of 13 to attend a monastic school in Phnom Penh. When Lon Nol usurped power from Sihanouk in 1970 during a bloodless coup, Hun Nal gave up his education to join the Khmer Rouge.Two years later, Hun Nal changed his name to Hun Sen. In 1974, Hun Sen met his future wife Bun Rany. He was wounded in the left eye, which was later removed, in 1975 on the day before the Khmer Rouge captured Phnom Penh. The following year, Hun Sen married Bun Rany.

Pol Pot (1975 - 1979)

Pol Pot(Saloth Sar) was born 19 May 1925 – 15 April 1998, was a Cambodian Communist revolutionary who led the Khmer Rouge from 1963 until his death in 1998. From 1963 to 1981, he served as the General Secretary of the Communist Party of Kampuchea. From 1976 to 1979, he also served as the prime minister of Democratic Kampuchea. Pol Pot became leader of Cambodia on April 17, 1975, and his rule was a dictatorship.During his time in power he imposed agrarian socialism, forcing urban dwellers to relocate to the countryside to work in collective farms and forced labor projects. The combined effects of executions, forced labor, malnutrition, and poor medical care resulted in the deaths of approximately 25 percent of the Cambodian population.In all, an estimated 1 to 3 million people (out of a population of slightly over 8 million) died as a result of the policies of his three-year premiership.

In 1979, after the Cambodian–Vietnamese War, Pol Pot fled to the jungles of southwest Cambodia, and the Khmer Rouge government collapsed.[12] From 1979 to 1997, he and a remnant of the old Khmer Rouge operated near the border of Cambodia and Thailand, where they clung to power, with nominal United Nations recognition as the rightful government of Cambodia. Pol Pot died in 1998 while under house arrest by the Ta Mok faction of the Khmer Rouge. Since his death, rumours that he was poisoned have persisted.

Marshal Lon Nol (1970 - 1975)
Marshal Lon Nol ( November 13, 1913 – November 17, 1985) was a Cambodian politician and general who served as Prime Minister of Cambodia twice, as well as serving repeatedly as Defense Minister. He led a military coup against Prince Norodom Sihanouk and became the self-proclaimed President of the newly created Khmer Republic.
Lon Nol was born in Prey Veng Province on November 13, 1913, to a family of mixed Chinese–Khmer descent.His father name Lon Hin, was the son of a Khmer Krom from Tay Ninh Province who later served as a district chief in Siem Reap and Kampong Thom, after making a name for himself 'pacifying' bandit groups in Prey Veng.His maternal grandfather was a Chinese immigrant from Fujian province who later became the governor of Prey Veng.Lon Nol was educated in the relatively privileged surroundings of the Lycée Chasseloup-Laubat in Saigon, followed by the Cambodian Royal Military Academy.

Norodom Sihaknouk King

Norodom Sihanouk (Khmer:31 October 1922 – 15 October 2012) was the King of Cambodia from 1941 to 1955 and again from 1993 to 2004. He was the effective ruler of Cambodia from 1953 to 1970. After his second abdication in 2004, he was known as "The King-Father of Cambodia" (Khmer: Preahmâhaviraksat), a position in which he retained many of his former responsibilities as constitutional monarch.
The son of King Norodom Suramarit and Queen Sisowath Kossamak Narirath, Sihanouk held so many positions since 1941 that the Guinness Book of World Records identifies him as the politician who has served the world's greatest variety of political offices.These included two terms as king, two as sovereign prince, one as president, two as prime minister, as well as numerous positions as leader of various governments-in-exile. He served as puppet head of state for the Khmer Rouge government in 1975–1976.
Most of these positions were only honorific, including the last position as constitutional king of Cambodia. Sihanouk's actual period of effective rule over Cambodia was from 9 November 1953, when Cambodia gained its independence from France, until 18 March 1970, when General Lon Nol and the National Assembly deposed him.