Sir Otto Frankel – whom I shall refer to as Otto because that is how we all addressed him – was a geneticist by training, plant breeder by occupation, cytologist by inclination and genetic conservationist by acclaim. Apart from his personal research, Otto was a highly effective builder and leader of research groups, Socratic gadfly to the scientific establishment, and high prophet of the genetic resources conservation movement. His career in science was unusual in that his most widely acclaimed work was done after his official retirement. A man of inexhaustible variety of opinions, Otto had a complex personality that could be rough or kindly, bored or engaged, impossible or altogether charming by turns, and he did not wish this memoir paint him otherwise. He refused to write an autobiographical sketch and did not keep many records. However, two interviews with him about his career were recorded, by Gavan McCarthy in 1985  and by Max Blythe in 1993 . Much of the information and views quoted here are from records of discussions I have had with him over many years.