Flann O'Riain (born 1929 in Hollyford, County Tipperary, died 6 December 2008) was a writer, political cartoonist, children's animator and language activist. He is best known for the children's TV series Daithí Lacha, broadcast on RTE in the 1960s, essentially a static comic strip shown one panel at a time, and Rí Rá agus Ruaille Buaille, also shown on RTE. As Doll he drew political cartoons for Comhar, Hibernia and the Irish Independent.
An Irish language activist, he resigned from the Comhairle na Gaeilge (Irish Language Council) in 1971 in protest at the closure of the Scoil Dún Chaoin (which was later reopened) and in 1977 was jailed for refusing to pay his TV licence in protest at what he saw as RTE's neglect of the language. Politically a nationalist, in the early 70s he and his wife Norita hosted an informal exchange programme with a northern Unionist couple.
He wrote a regular column for The Irish Times in the 1980s, "Where's That?", exploring the origins of Irish placenames. His books include Lazy Way to Irish (1995), Lazy Way to Welsh (1995) and Townlands of Leinster and the People Who Lived There (2000).