Ioan Duma (November 5, 1896 — July 16, 1981) was a Romanian cleric and a titular bishop of the Roman Catholic Church.
Born in Valea Mare, Bacău County, he studied at the Franciscan seminary in Hălăucești and in Rome.
Ordained there in 1924, he returned to Romania to serve in the parishes at Săbăoani and Hălăucești, also teaching at the seminary in the latter place, and officiating at Franciscan convents in Transylvania in 1944.
In 1948, nuncio Gerald Patrick O'Hara consecrated him bishop in secret, without the approval of the new communist authorities.
Sentenced to four years' imprisonment for "spying on behalf of the Vatican", he was released when his term expired in 1955 and forced to live and work as a parish priest first in Iași, then in Mihail Kogălniceanu, Constanța County.