Alphonso or Alfonso is a masculine given name and occasional nickname which may refer to:

• Alfonso I of Aragon (1104–1134), known as el Batallador (The Battler)
• Alfonso I of Asturias (739–757)
• Alfonso II of Aragon (1162–1196)
• Alfonso II of Asturias (791–842)
• Alfonso II of Naples (1448–1495)
• Alfonso III of Aragon (1285–1291)
• Alfonso III of León (866–910)
• Alfonso IV of Aragon (1327–1336)
• Alfonso IV of León (925–931)
• Alfonso V of Aragon (1416–1458), also king of Naples and Sicily
• Alfonso V of León (999–1028)
• Alfonso VI of León (1065–1109)
• Alfonso VII of León (1126–1157)
• Alfonso VIII of Castile (1158–1214)
• Alfonso IX of León (1188–1230)
• Alfonso X of Castile (1252–1284)
• Alfonso XI of Castile (1312–1350)
• Alfonso XII of Spain (1857–1885) (ordinal numbering continues from the kings of Castile)
• Alfonso XIII of Spain (1886–1931)
• Alfonso Fróilaz, briefly king of the unified kingdom of Asturias, Galicia and León in 925
• Alfonso, Prince of Asturias (1453–1468), figurehead of rebelling magnates against his brother King Henry IV of Castile
• Infante Alfonso of Spain (1941–1956), younger brother of King Juan Carlos of Spain
• Alfonso of Spain, Prince of Asturias, heir apparent of the throne of Spain

• Alfonso I d'Este (1476–1534), Duke of Ferrara
• Alfonso II d'Este (1533–1597), Duke of Ferrara
• Alfonso II, Count of Provence (1180–1209), second son of Alfonso II of Aragon
• Alfonso III d'Este (1591–1644), Duke of Modena and Reggio
• Alfonso of Capua (c. 1120–1144), Prince of Capua
• Prince Alfonso, Count of Caserta (1841–1934), Duke of Calabria and head of the royal house of the Two Sicilies
• Prince Alfonso of Hohenlohe-Langenburg (1924–2003), Spanish playboy and businessman
• Alfonso Jordan (1103–1148), Count of Tripoli, Count of Rouergue, Count of Toulouse, Margrave of Provence and Duke of Narbonne
• Infante Alfonso, Duke of Calabria (1901–1964), claimant to the title of the head of House of Bourbon Two Sicilies
• Alphonso, Earl of Chester (1273–1284), first son of Edward I of England, heir apparent to the English throne
• Prince Alfonso of Liechtenstein (born 2001), grandson of Hans-Adam II

• Alfonso of Valladolid (c. 1270–c. 1347), Jewish convert to Christianity, philosopher, and mathematician
• Alphonso Calhoun Avery (1835–1913), American lawyer, Confederate military officer and politician
• Alphonso Boone (1796–1850), American pioneer in what is now Oregon
• Alfonso Calderon (activist) (born 2001), Spanish-born American gun control activist
• Alfonso Calderón (poet) (1930–2009), Chilean poet and writer
• Al Campbell (born 1954), Jamaican reggae singer
• Alphonso Carreker (born 1962), American former National Football League player
• Alfonso Cuarón (born 1961), Mexican cinematographer
• Alphonso Giovanni Giuseppe Roberto D'Abruzzo, birth name of Robert Alda (1914–1986), American actor
• Alphonso Joseph D'Abruzzo, birth name of Alan Alda (born 1936), American actor, son of Robert Alda
• Alphonso Davies (born 2000), Ghanaian-born Canadian soccer player
• Mike Espy (born 1953), American lawyer and politician
• Alphonso Ford (1971–2004), American basketball player
• Alphonso Gerard (1916–2002), American Negro league baseball player
• Alphonso Jackson (born 1945), American politician, United States Secretary of Housing and Urban Development
• Alphonso Johnson (born 1951), American jazz bassist
• Buck Johnson (born 1964), American former basketball player
• Alfonso Lizarazo (born 1940), Colombian host and politician
• Alphonso Lingis (1933–2025), American philosopher, writer and translator
• Alphonso Lisk-Carew (1883–1969), Sierra Leonean photographer
• Alphonso M. Lunt (1837–1917), Union Army sergeant awarded the Medal of Honor
• Alphonso McAuley, 21st century American actor
• Alfonso Mejia-Arias (born 1961), Mexican musician, writer, social activist and politician
• Alfonso Oiterong, Palauan politician, vice president
• Alfonso Pérez (born 1972), Spanish former footballer
• Alfonso Pérez (boxer) (born 1949), Colombian former boxer
• Alfonso Quiñónez Molina (1874–1950), Salvadoran politician, physician, and president (1913–1914, 1918–1919, 1923–1927)
• Alfonso Ribeiro (born 1971), American actor and game show host
• Alphonso Theodore Roberts (1937–1996), Vincentian political activist and cricketer
• Alfonso John Romero (born 1967), American video game designer
• Alphonso Sgroia (1886–1940), New York City gangster and murderer
• Alphonso Smith (born 1985), American former National Football League player
• Alphonso C. Smith (1894–1945), Canadian politician
• C. Alphonso Smith (1864–1924), American English professor, college dean, philologist and folklorist
• Alfonso Soriano (born 1976), American Major League Baseball player
• Alphonso Sumner, African American newspaper publisher and abolitionist who opened Nashville, Tennessee's first Black school in 1833
• Alphonso Taft (1810–1891), American jurist, diplomat, and politician, United States Attorney General and Secretary of War under President Ulysses S. Grant, father of President William Howard Taft
• Alphonso Wilson (1860–1936), African-American activist
• Alphonso Wood (1810–1881), American botanist and theology instructor

• Alphonso Cox (1908–1964), American Negro league pitcher
• Alphonso Sharland, member of the pop rock band The Hoosiers

• Don Alfonso, in Mozart's opera Così fan tutte
• Alphonso, protagonist in Alfonso und Estrella, an opera by Franz Schubert
• Alphonso Ali, a minor character in the comic strip Bloom County
• Alfonzo Dominico Jones, a dog in the Australian television series SeaChange
• Al MacKenzie, a Marvel Comics character
• Alfonso "French" Sosa, a main character from The OA, an American television series

• "Alfonso" (song), a 2013 song by Levante
• Alphonsus Liguori (1696–1787), Roman Catholic theologian
• Alphons