John Ottis Adams (1851 – 1927) was an American impressionist painter and member of the Hoosier Group of Indiana painters.
He spent his youth in Franklin, Shelbyville, and Martinsville, Indiana and attended Wabash College for two years.
Adams studied art at the South Kensington School of Art in London for two years. He settled in Muncie in 1876 and opened a studio there in 1887 after spending seven years doing further art study in Munich with T. C. Steele and other members of the Hoosier Group. Adams was the central figure in the formation of an art school in Muncie, Indiana, where he later participated in forming the Art Students League of Muncie, after the Muncie Art School closed.
Adams later, with other members of the Hoosier Group, founded the Herron School of Art in Indianapolis. He and his wife, Winifred Brady Adams, also a painter, lived and painted at The Hermitage in Brookville, Indiana along with T. C. Steele and his wife.
Together with William Forsyth, Adams also instructed American impressionist artist Francis Focer Brown (1891–1971). He taught many students, including Dorothy Morlan.