Umberto I, King of Italy or Humbert I of Italy (Umberto Ranieri Carlo Emanuele Giovanni Maria Ferdinando Eugenio di Savoy), (14 March 1844 – 29 July 1900) was the King of Italy from 9 January 1878 until his death. He was deeply loathed in left-wing circles, especially among anarchists, because of his hard-line conservatism and support of the Bava Beccaris massacre in Milan. He was killed by anarchist Gaetano Bresci one year after the incident. He was the only modern King of Italy to be assassinated.

The son of Vittorio Emanuele II and of Adelaide, archduchess of Austria, Umberto was born in Turin, then capital of the kingdom of Sardinia, on March 14, 1844. His education was entrusted to, amongst others, Massimo Taparelli, marquis d'Azeglio and Pasquale Stanislao Mancini. Since March 1858 he had a military career in the Sardinian army, beginning with the rank of captain. Umbreto took part to the Italian Wars of Independence: he was present at the battle of Solferino in 1859, and in 1866 commanded the XVI Division at the Villafranca battle that followed the Italian defeat at Custoza. On 21 April 1868 Umberto married his first cousin, Margherita Teresa Giovanna, Princess of Savoy. Their son was Victor Emmanuel, prince of Naples; later Victor Emmanuel III of Italy. Ascending the throne on the death of his father (January 9, 1878), Umberto adopted the title "Umberto I of Italy" rather than "Umberto IV" (of Savoy), and consented that the remains of his father should be interred at Rome in the Pantheon, and not in the royal mausoleum of Basilica of Superga.

While on a tour of the kingdom, accompanied by Premier Benedetto Cairoli, he was attacked by an anarchist, Giovanni Passannante, during a parade in Naples on (November 17, 1878). The king warded off the blow with his sabre, but Cairoli, in attempting to defend him, was severely wounded in the thigh. The would-be assassin was condemned to death, but the king commuted the sentence to one of penal servitude for life. The incident upset the health of Queen Margherita for several years. The reign of Umberto I was a time of social upheaval, though it was later claimed to have been a tranquil belle époque. Social tensions mounted as a consequence of the relatively recent occupation of the kingdom of the two Sicilies, the spread of socialist ideas, public hostility to the colonialist plans of the various governments, especially Crispi's, and the numerous crackdowns on civil liberties. The protesters included the young, then left-wing, Benito Mussolini.

In foreign policy Umberto I approved the Triple Alliance with Austria-Hungary and Germany, repeatedly visiting Vienna and Berlin. Many in Italy, however, viewed with hostility an alliance with the former Austrian enemies in the independence wars, who were still occupying areas claimed by Italy. He was also favourably disposed towards the policy of colonial expansion inaugurated in 1885 by the occupation of Massawa. He was suspected of aspiring to a vast empire in north-east Africa, a suspicion which tended somewhat to diminish his popularity after the disaster of Adowa on 1 March 1896. During the colonial wars in Africa, large demonstrations over the rising price of bread were held in Italy and on May 7, 1898 the city of Milan was put under military control by General Fiorenzo Bava-Beccaris, who ordered the use of cannons on the demonstrators; as a result, about 100 people were killed according to the authorities (even though some claim the death toll was about 350); about a thousand were wounded. King Umberto sent a telegram to congratulate Bava Beccaris on the restoration of order and later decorated him with the medal of Great Official of Savoy Military Order, greatly outraging a large part of the public opinion.

To a certain extent his popularity was enhanced by the firmness of his attitude towards the Vatican, as exemplified in his telegram declaring Rome "untouchable" (20 September 1886), and affirming the permanence of the Italian possession of the "Eternal City". Being increasingly unpopular, Umberto I was victim of yet another murder attempt, by an unemployed ironsmith, Pietro Acciarito, who tried to stab him near Rome on 22 April 1897.

Finally, he was murdered with four revolver shots by the Italo-American anarchist Gaetano Bresci in Monza, on the evening of 29 July 1900. Bresci claimed he wanted to avenge the people killed by Bava Beccaris. Official propaganda of the day gave the assassinated king the nickname "the Good". He was buried in the Pantheon in Rome, by the side of his father Victor Emmanuel II, on 9 August 1900. He was also the last Savoy to be buried there, as his son and successor Victor Emmanuel III died in exile.