Nature had made him mean, the smallpox had made him hideous, and his degraded habits made him loathsome. And Peter had all the sentiments of the worst kind of small German prince of the time. He had the conviction that his princeship entitled him to disregard decency and the feelings of others. He planned brutal practical jokes, in which blows had always a share. His most manly taste did not rise above the kind of military interest which has been defined as "corporal's mania," the passion for uniforms, pipeclay, buttons, the "tricks of parade and the froth of discipline." He detested the Russians, and surrounded himself with Holsteiners.
Peter was born in Kiel, in the duchy of Holstein-Gottorp. His parents were Charles Frederick, Duke of Holstein-Gottorp (a nephew of Charles XII of Sweden), and Anna Petrovna (a daughter of Emperor Peter I and Empress Catherine I of Russia). His mother died three months after his birth. In 1739, Peter's father died, and he became Duke of Holstein-Gottorp as Charles Peter Ulrich (German: Karl Peter Ulrich) at the age of 11.
When Elizabeth, his mother's younger sister, became Empress of Russia, she brought Peter from Germany to Russia and proclaimed him her heir presumptive in the autumn of 1742. Previously in 1742, the 14-year-old Peter was proclaimed King of Finland during the Russo-Swedish War (1741–1743), when Russian troops held Finland. This proclamation was based on his succession rights to territories held by his childless great-uncle, the late Charles XII of Sweden, who also had been Grand Duke of Finland. About the same time, in October 1742, he was chosen by the Swedish parliament to become heir presumptive to the Swedish throne. However, the Swedish parliament was unaware of the fact that he had also been proclaimed heir presumptive to the throne of Russia, and when their envoy arrived in Saint Petersburg in November, it was too late. It has been reported that the succession rights to Sweden of the underage Peter were renounced on his behalf. Also in November, Karl Peter Ulrich converted to Eastern Orthodoxy under the name of Peter Fedorovich.
Empress Elizabeth arranged for Peter to marry his second cousin, Sophia Augusta Frederica (later Catherine the Great), daughter of Christian August, Prince of Anhalt-Zerbst and Johanna Elisabeth of Holstein-Gottorp. The young Princess formally converted to Russian Orthodoxy and took the name Ekaterina Alexeievna (i.e., Catherine). They married on 21 August 1745. The marriage was not a happy one but produced one son, the Future Emperor Paul, and one daughter, Anna Petrovna (20 December 1757 – 19 March 1759). Catherine later claimed that Paul was not fathered by Peter: that, in fact, they had never consummated the marriage. During the sixteen years of their residence in Oranienbaum, Catherine took numerous lovers, while her husband did the same in the beginning.
One of his most popular reforms was the manifesto of February 1762 that exempted the nobility from obligatory state and military Service (established by Peter the Great) and gave them freedom to travel abroad. On the day Peter submitted this manifesto, the parliament proposed building a pure gold statue of him, but Peter refused, saying that there must be much better uses for gold in the country.
After his death, four fake Peters (five if Šćepan Mali of Montenegro is included) came forth, supported by revolts among the people, who believed in a rumor that Peter had not died but had been secretly imprisoned by Catherine. The most famous was the Cossack Yemelyan Pugachev, who led what came to be known as Pugachev's Rebellion in 1774, which was ultimately crushed by Catherine's forces. In addition, Kondratii Selivanov, who led a castrating sect known as the Skoptsy, claimed to be both Jesus and Peter III.
In December 1796, after succeeding Catherine, Peter's son and Emperor Paul, who disliked his mother's behaviour, arranged for Peter's remains to be exhumed and reburied with full honors in the Peter and Paul Cathedral, where other tsars were buried.
The classical view of Peter's character is mainly drawn out of the memoirs of his wife and successor. She described him as an "idiot", "drunkard from Holstein", "good-for-nothing", etc. This portrait of Peter can be found in most history books, including 1911 Encyclopædia Britannica:
Peter has been depicted on screen a number of times, almost always in films concerning his wife Catherine. He was portrayed by Douglas Fairbanks, Jr. in the 1934 film The Rise of Catherine the Great and by Sam Jaffe in The Scarlet Empress the same year. In 1991 Reece Dinsdale portrayed him in the television series Young Catherine. La Tempesta (1958) depicts Yemelyan Pugachev's effort to force his recognition as Peter III and offers a critical view of Catherine the Great, with Van Heflin in the role of Pugachev and Viveca Lindfors as Catherine. He was also depicted as a cowardly, drunken, wife beater in the Japanese anime Le Chevalier D'Eon. He also appears in the 2014 TV series played by Aleksander Yatsenko.
The legend of Peter is still talked about, especially in the town where he lived most of his life, former Oranienbaum, later Lomonosov, situated on the southern coast of the Gulf of Finland, 40 km west of St. Petersburg. Peter's palace is the only one of the famous palaces in the St. Petersburg area that was not captured by the Germans during Second World War. During the war, the building was a school and people say the ghost of Peter protected the children of Oranienbaum from getting hurt by bombs. Furthermore, it was near this town that the siege of Leningrad ended in January 1944. People say that Peter, after his death, stopped Hitler's army near Leningrad, just as the living Peter had stopped the Russian army near Berlin.
During his 186-day period of government, Peter III passed 220 new laws that he had developed and elaborated during his life as a crown Prince. Elena Palmer claims that his reforms were of a democratic nature. He proclaimed religious freedom — in those times a revolutionary step, that not even the advanced Western Europe had taken. He fought corruption within government, established public litigation and abolished the secret police — a repressive organ started under Peter I – and intended to expose it as betrayer of the state for its mercilessness and torture methods. Catherine recreated this institution, and it remained present in Russia thereon. Peter established obligatory education for aristocrats; all aristocrats had to provide their children with education and report it to the senate. Furthermore, in some cities technical schools were established for middle and lower class children. Peter began the reorganization and modernization of the Russian army.