Arthur is a common masculine given name. Its etymology is disputed, but its popularity derives from its being the name of the legendary hero King Arthur.

Art is a diminutive form of the name. A common spelling variant used in many Slavic, Romance, and Germanic languages is Artur.

The origin of the name Arthur remains a matter of debate. Some suggest it is derived from the Roman nomen gentile (family name) Artōrius, of obscure and contested etymology (but possibly of Messapic or Etruscan origin). Some scholars have suggested that is relevant to this debate that the legendary King Arthur's name only appears as Arthur, or Arturus, in early Latin Arthurian texts, never as Artōrius (although Classical Latin Artōrius became Arturius in some Vulgar Latin dialects). However, this may not say anything about the origin of the name Arthur, as Artōrius would regularly become Art(h)ur when borrowed into Welsh.

Another possibility is that it is derived from a Brittonic patronym *Arto-rīg-ios (the root of which, *arto-rīg- "bear-king" is to be found in the Old Irish personal name Art-ri) via a Latinized form Artōrius. Less likely is the commonly proposed derivation from Welsh arth "bear" + (g)wr "man" (earlier *Arto-uiros in Brittonic); there are phonological difficulties with this theory - notably that a Brittonic compound name *Arto-uiros should produce Old Welsh *Artgur and Middle/Modern Welsh *Arthwr and not Arthur (in Welsh poetry the name is always spelled Arthur and is exclusively rhymed with words ending in -ur - never words ending in -wr - which confirms that the second element cannot be [g]wr "man").