Ian or Iain is a name of Scottish Gaelic origin, which is derived from the Hebrew given name יוֹחָנָן‎ (Yohanan, Yôḥānān) and corresponds to the English name John. The spelling Ian is an Anglicization of the Scottish Gaelic forename Iain. This name is a popular name in Scotland, where it originated, as well as in other English-speaking countries.

The name has fallen out of the top 100 male baby names in the United Kingdom, having peaked in popularity as one of the top 10 names throughout the 1960s.^[2] In 1900, Ian ranked as the 180th most popular male baby name in England and Wales.^[3] As of 2019^[update], the name has been in the top 100 in the United States every year since 1982, peaking at 65 in 2003.^[4]

Other Gaelic forms of the name "John" include "Seonaidh" ("Johnny" from Lowland Scots), "Seon" (from English), "Seathan", and "Seán" and "Eoin" (from Irish). The Welsh equivalent is Ioan, the Cornish counterpart is Yowan and the Breton equivalent is Yann.

• Iain Anders (1933–1997), English actor
• Iain Andrews (born 1975), contemporary English painter
• Iain Archer, Northern Irish Singer-songwriter musician
• Iain Armitage (born 2008), American child actor
• Iain Baird (born 1971), Canadian soccer defender
• Iain Ballamy (born 1964), British composer, soprano, alto and tenor saxophone player
• Iain Balshaw (born 1979), English rugby player
• Iain Bell (born 1980), English composer
• Iain Banks (1954–2013), Scottish writer
• Iain Benson (born 1955), legal philosopher, writer, professor and practising legal consultant
• Iain Black (born 1967), British Columbia politician
• Iain Boal, Irish social historian of technics and the commons
• Iain Borden (born 1962), English architectural historian and urban commentator
• Iain Brambell (born 1973), Canadian rower
• Iain Brines (born 1967), former Scottish football referee in the Scottish Premier League
• Iain Brunnschweiler (born 1979), English cricketer
• Iain Canning (born 1979), English film producer
• Iain Chambers, English composer, producer and performer
• Iain Michael Chambers, British scholar
• Iain Cheeseman, Australian scientist
• Iain Chisholm (born 1985), Scottish footballer
• Iain Clough (born 1965), British slalom canoer
• Iain Collings, Australian scientist
• Iain Connell (born 1977), Scottish comedian and actor
• Iain Coucher (born 1961), British businessman and consultant in the railway industry
• Iain Couzin, British scientist
• Iain Dale (born 1962), British broadcaster, author and political commentator
• Iain Davidson (born 1984), Scottish professional footballer
• Iain De Caestecker (born 1987), Scottish actor
• Iain Dilthey (born 1971), British film director
• Iain Donald Campbell (1941–2014), Scottish biophysicist and academic
• Iain Dowie (born 1965), Northern Irish football manager
• Iain Duncan (born 1963), Canadian ice hockey forward
• Iain Dunn (born 1970), English professional footballer
• Iain Durrant (born 1966), Scottish footballer
• Iain Eairdsidh MacAsgaill (1898–1934), Scottish poet and piper
• Iain Evans (field hockey) (born 1981), South African field hockey player
• Iain Fairley (born 1973), Scottish rugby union player
• Iain Fearn (born 1949), Scottish footballer
• Iain Finlay (born 1935), Australian author
• Iain Finlayson (alpine skier) (1951–1990), British alpine skier
• Iain Glen (born 1961), Scottish actor, noted for his role in TV's Game of Thrones
• Iain Gray (born 1957), Leader of Labour in the Scottish Parliament
• Iain Hamilton (disambiguation), multiple people
• Iain Harnden (born 1976), Zimbabwean hurdler
• Iain Henderson (born 1992), professional rugby player for Ulster, Ireland and the British & Irish Lions
• Iain Kay (born 1949), Zimbabwean farmer and politician
• Iain Lee (born 1973), British comedian, TV presenter and radio presenter
• Iain Lindsay (born 1959), British diplomat
• Iain Macleod (1913–1970), British politician
• Iain Macmillan (1938–2006), Scottish photographer, noted for his image of the Beatles walking across Abbey Road
• Iain Matthews (born 1946), formerly known as Ian Matthews, English musician, singer-songwriter, member of Fairport Convention
• Iain David McGeachy (1948–2009), birth name of John Martyn, British singer-songwriter and guitarist
• Iain McGilchrist (born 1953), psychiatrist, writer, and former Oxford literary scholar
• Iain McKenzie (born 1959), Scottish politician
• Iain Morrison (rugby union) (born 1962), Scottish rugby union player
• Iain Morrison (born 1983), English rugby league player
• Iain Morrison (musician), Scottish musician
• Iain O'Brien (born 1976), New Zealand cricketer
• Iain Paxton (born 1957), Scottish rugby player
• Iain Robertson (born 1981), Scottish actor
• Iain Smith (Scottish politician) (born 1960), Scottish politician
• Iain Duncan Smith (born 1954), Leader of the Conservative Party, 2001–2003
• Iain Softley (born 1958), film director
• Iain Stirling (born 1988), Scottish TV presenter and comedian
• Iain Stewart (disambiguation), multiple people
• Iain Sutherland (1948–2019), Scottish musician, member of The Sutherland Brothers
• Iain Sydie (born 1969), Canadian badminton player
• Iain Torrance (born 1949), President of Princeton Theological Seminary and former Moderator of the General Assembly of the Church of Scotland

• Ian – the supporting character from Shinbi's Haunted House anime
• Ian – from Shane Jiraiya Cummings' short story "Ian"; every male character the protagonist meets is called Ian
• Ian – from Sarah Kane's play Blasted
• Ian – from Leprechaun 2
• Ian – the protagonist in the manga Not Simple by Natsume Ono
• Ian Beale – from the TV soap opera EastEnders
• Ian Chesterton – from the TV series Doctor Who
• Ian Craig – from the radio soap opera The Archers
• Ian the Deer – Elliot's arch-rival in the Open Season movies
• Ian Doyle – an Irish terrorist featured on Criminal Minds
• Ian Edgerton – FBI agent and sniper from the show Numb3rs
• Ian Foot – from the British TV series Come Fly with Me
• Ian Gallagher – one of the main characters in the television drama Shameless and its American remake
• Ian Grimm – creative director of fictional video game in the television series Mythic Quest
• Ian Hainsworth – Susan Delfino's boyfriend in 3rd season of Desperate Housewives
• Ian Hawke – the main antagonist in the Alvin and the Chipmunks movies
• Ian Howe – an antagonist in National Treasure
• Ian Kabra – antagonist of the book series The 39 Clues
• Ian Kelley – title character from the Canadian animated series Being Ian, created by Ian James Corlett, voiced by Richard Ian Cox
• Ian Lewis and Ian Ketterman (together with dozens of other Ians) – characters created by Lee and Herring; the duo used 'Ian' as their de facto comedy name, in such sketches as the Ian News
• Ian Lightfoot – Tom Holland’s character from the film Onward
• Ian Malcolm (Jurassic Park) – from Michael Crichton's novel Jurassic Park
• Ian (MÄR) – a recurring character in the manga and anime series MÄR
• Ian Maxtone-Graham – from the TV series Suddenly Susan
• Professor Ian McClaine – adoptive father of Joe 90
• Ian McKenzie – the liberal attorney from the novel and the film A Dry White Season
• Ian McKinley – from the movie Final Destination 3
• Ian Miller – from the movie My Big Fat Greek Wedding
• Ian Murray – the nephew of Jamie Fraser in Diana Gabaldon's Outlander series
• Ian Nottingham – a character from Witchblade comic and TV series
• Ian O'Shea – from Stephenie Meyer's novel The Host
• Ian Papov – character and member of the Demolition Boys (also known as the Blitzkrieg Boys) from the anime series Beyblade (2000)
• Ian Randall – from the Smallville (TV series), episodes "Dichotic" and "Asylum", a character who had the ability to duplicate himself
• Ian Raymond – Laura's boyfriend in the novel and film High Fidelity
• Ian Rider – from the Alex Rider books
• Ian Schulenburg – unseen husband of Harriet Schulenburg in Green Wing
• Ian Scuffling – Tyrone Slothrup's adopted name after he goes into hiding in Thomas Pynchon's Gravity's Rainbow
• Ian Slater – from the ABC soap opera All My Children
• Ian Thomas – Ryan Merriman's character in the TV series Pretty Little Liars
• Janis Ian – from the film Mean Girls

• Iain Sterling, a fictional character in the Android: Netrunner universe
• Iain Dean, a fictional character in the Casualty Central universe

• John (given name), a common masculine given name in the English language of originally Semitic origin
• Eoin
• Ioan
• Ian (disambiguation)
• IANS (disambiguation)