Magnus, meaning "great" in Latin, was used as cognomen in ancient Rome and a given name in the Middle Ages.

• Pompey Magnus, Roman consul and general who was given the honorific "Magnus"
• Magnus Maximus, Roman usurper and Western Roman Emperor (died 388)
• Montius Magnus, 4th-century Roman quaestor

• Magnus I of Norway (1024–1047)
• Magnus II of Norway (1048–1069)
• Magnus III of Norway (1073–1103)
• Magnus IV of Norway (c. 1115–1139)
• Magnus V of Norway (1156–1184)
• Magnus VI of Norway (1238–1280)
• Magnus VII of Norway, also known as Magnus Eriksson (1316–1374)

• Magnus the Strong (c. 1106–1134)
• Magnus Henriksson (died 1161)
• Magnus Ladulås (1240–1290)
• Magnus Eriksson (1316–1374), also Magnus VII of Norway

• Géza I (1074–1077), also known by his baptismal name Magnus
• Magnus the Good (1042–1047), also Magnus I of Norway
• Magnus, Duke of Holstein (1540–1583), titular King of Livonia from 1570 to 1578
• Magnús Óláfsson (died 1265), King of Mann and the Isles

• Magnus, Duke of Saxony (c. 1045–1106)
• Magnus I, Duke of Brunswick-Lüneburg (before 1318–1369)
• Magnus II, Duke of Brunswick-Lüneburg (1324–1373), also known as Magnus with the Necklace
• Magnus I, Duke of Saxe-Lauenburg (1488–1543)

• Albert Magnus (c.1200–1280), German bishop, philosopher, theologian and scientist
• Magnus (bishop of Milan), bishop of Milan from 518 to c.530
• Magnus Erlendsson, Earl of Orkney, Earl of Orkney 1106–c.1117)
• Magnus of Anagni (2nd century)
• Magnus of Avignon (died 660), bishop and governor of Avignon
• Magnus of Cuneo (3rd century)
• Magnus of Füssen, missionary saint of southern Germany, seventh or eighth century

• Magnus family, British Jewish
  • Magnus baronets
    • Philip Magnus, 1st Baronet
    • Philip Magnus (historian), 2nd Baronet (1906–1988), British historian
    • Laurie Magnus (executive), 3rd Baronet (born 1955), British executive, appointed UK Prime Minister's Independent Adviser on Ministers' Interests in 2022
    • Laurie Magnus (1872–1933), English author, journalist, and publisher
  • Katie Magnus, author and communal worker, wife of Philip Magnus, 1st Baronet
  • Leonard Arthur Magnus, scholar and translator, son of Philip Magnus, 1st Baronet
• Ailsa Magnus (born 1967), Scottish sculptor
• Désiré Magnus, Belgian pianist
• Elisabeth von Magnus, Austrian singer
• Finn Magnus, Danish-American founder of Magnus Harmonica Corporation
• Heinrich Gustav Magnus, German chemist and physicist who discovered the Magnus effect
• Kurt Magnus (1912–2003), German scientist, expert in the field of applied mechanics, a pioneer of mechatronics
• Kurt Magnus (radio personality) (1887–1962), German lawyer and politician, a pioneer of German radio broadcasting
• Ludwig Immanuel Magnus, German mathematician
• Paul Wilhelm Magnus, German botanist
• Siobhan Magnus, American singer
• Thomas Magnus (d. 1550), English churchman and diplomat
• Wilhelm Magnus, German mathematician

• Magnus, pseudonym of American magician Jeff McBride
• Magnus, pen name of Italian comic book artist Roberto Raviola
• Magnus (formerly Brutus Magnus), ring name of English professional wrestler Nick Aldis (born 1986)

• Magnus Bane, in The Mortal Instruments series by Cassandra Clare, and character in the TV Series Shadowhunters
• Magnus Burnsides, one of the main protagonists in The Adventure Zone Dungeons & Dragons podcast
• Magnus Chase, the main protagonist in the fantasy series Magnus Chase and the Gods of Asgard
• Magnus Eisengrim, in the Deptford Trilogy
• Magnus Gallant, a main character in Ogre Battle 64
• Magnus Greel, a villain in the 1977 Doctor Who serial The Talons of Weng-Chiang
• Magnus Hammersmith, an antagonist in Metalocalypse
• Magnus Murchie, Margaret's insane uncle and advisor in Muriel Spark's Symposium
• Magnus Pym, the protagonist of John le Carré's novel A Perfect Spy
• Magnus Powermouse, the title character of the children's book of the same name
• Magnus, Robot Fighter, a comic book character published by Gold Key and Valiant comics
• Magnus von Grapple, a boss in Paper Mario: The Thousand-Year Door
• Magnus (The Vampire Chronicles), in The Vampire Chronicles by Anne Rice
• Magnus, the real name of the Doctor Who character the Master
• Ultra Magnus, several characters in the Transformers universe
• Magnus Lehnsherr, an alternate reality Marvel Comics character; son of Rogue and Magneto
• Magnus the Red, Primarch of the Thousand Sons Space Marines in the Warhammer 40,000 universe
• Magnus the Sorcerer, a Marvel Universe character
• Magnus, in the video game Kid Icarus: Uprising
• Magnus Fossbakken, in the Norwegian TV show Skam
• Magnus Nielsen, a character from the TV series Dark
• Magnus the Rogue, a supporting character in the video game Minecraft Story Mode
• Magnus, the mascot of the Cleveland State Vikings
• Magnus, the god of magic from The Elder Scrolls universe
• Will Magnus, a DC Comics scientist
• Count Magnus, title character in the M.R. James story
• Jonah Magnus, founder of the titular institute in the horror fiction podcast The Magnus Archives
• Magnus au Grimmus, a character in the Red Rising series
• Ultra Magnus, a supporting character in Transformers: Animated, in which "magnus" is a high rank amongst Autobots; he also appears in Transformers: Prime
• Magnus Honey, Miss Honey's dad in Matilda (novel)

• All pages with titles containing Magnus
• Magnes (disambiguation)
• Magnusson (disambiguation)
• List of people known as The Great