He was born Santiago Ontañón Fernández on November 22nd 1903 in Santander, Spain. He had 3 sisters.
His family moved to Madrid when he was still young. In the early 1920’s he lived in Paris, where he worked as an illustrator for magazines and in 1923 he built his first stage design for a performance by the Russian Ballet. He returned to Madrid in 1927 where he built a reputation as a theatrical set designer and from the start of the 1930’s he began working in films, both as an actor and designer.
When the Spanish Civil War began in 1936, Santiago enlisted as a soldier of the republican cavalry while continuing to design sets and costumes for theatrical productions and writing and illustrating for magazines. In 1939, with the republicans defeated, Santiago applied for political asylum in Chile. While there he married a woman named Nana Bell and the couple would move around South America, first to Uruguay, then Argentina, where he contiuned to design sets for stage productions and eventually Peru.
At some point in the mid-1950’s he returned to Spain, where, in addition to theatrical projects, from 1957 onwards he would resume his cinematic career on both sides of the camera. He would then continue working in cinema throughout the 60’s and 70’s, retiring in the early 1980’s. In 1988 he published his memoirs in the book “Unos pocos amigos verdaderos“ (A few true friends).
He died in Madrid on August 26th 1989 at the age of 85.
The bulk of Santiago’s biographical details come from his profile on the Enciclopedia del Cine Español website. His biography there goes into far more detail, particularly in regard to his activities outside film-making.
I did find a few undocumented appearances by Santiago in films where he has production credits so there may be more roles to be found.
- La traviesa molinera .... The Miller (poster credit - role unconfirmed)
- Por un perro chico, una mujer .... role unknown (poster credit)
1936 - Una mujer en peligro .... Ricardo (poster credit - role unconfirmed)
1957 - Faustina .... Don Fernando (credited)
1958 - La vida por delante .... Patient 'Sra. de Anglada' (credited)
- Muchachas en vacaciones .... Uncle Abelardo (credited)
1959 - El día de los enamorados .... Tony (credited)
- La vida alrededor .... Business partner (credited)
- Miss Cuplé .... Director (credited)
1960 - Amor bajo cero .... Rear admiral (credited)
- Días de feria .... President of the jury at the milking contest (credited)
- Miss Cuplé .... Director (credited)
- Mi calle .... (credited, but not found)
- Sólo para hombres .... Early customer (credited)
1961 - ¡Adiós, Mimí Pompón! .... Bernardo Chamonix (credited)
- El pobre García .... Don Alfredo (credited)
- Ha llegado un ángel .... Producer (credited)
- Honorables sinvergüenzas .... Don Leon (credited)
- Julia y el celacanto .... Professor Alessandro Poppi (credited)
- La rosa roja .... role unknown (credit unknown)
- Siempre es domingo .... Card player (credited)
1962 - La gran familia .... Examiner (credited)
- Tómbola .... Insurance advisor (credited as "S. Ontañón")
1963 - El verdugo .... Sr. Corcuera (credited)
- Le avventure di Scaramouche .... Member of the theatre troupe (credited)
1964 - Búsqueme a esa chica .... Promoter (credited)
- La Tulipe Noire .... Nobleman robbed by The Black Tulip (credited)
- Los dinamiteros .... Doorman (credited)
- Rueda de sospechosos .... Don Pablo (credited)
1965 - La familia y... uno más .... Don Andreas (credited)
- Un lugar llamado Glory .... Mayor (credited)
1966 - El arte de no casarse .... Doctor (credited)
- El Greco .... Pompeionio (uncredited)
- I sette falsari .... Funeral director (uncredited)
- Tres perros locos, locos .... Monk (credited)
1967 - De cuerpo presente .... Man who dies in the dance-off (credited)
- Escuela de matrimonios (TV series) Ep. 11: "Maridos a gogó" .... role unknown (credited)
- La familia Colón (TV series) Ep. 11: "Se necesita auténtico gancho" .... Producer (credited)
1969 - ¡¡Se armó el belén!! .... Set decorator (uncredited as actor)
- Marquis de Sade: Justine .... Priest who takes Justine's money (uncredited as actor)
- No disponible .... Don Gregorio (uncredited)
- The Castle of Fu Manchu .... Governor of Anatolia (uncredited as actor)
1970 - Crimen imperfecto .... Drunken guest (credited)
- El mesón del gitano .... Impresario (uncredited as actor)
1971 - Blanca por fuera y Rosa por dentro .... Don Felix (credited)
- Varietés .... Decorator (uncredited as actor)
1972 - Dans la poussière du soleil .... Banker (uncredited as actor)
1973 - Las señoritas de mala compañía .... Don Faustino (uncredited as actor)
- No encontré rosas para mi madre .... Man leaving the ship (uncredited as actor)
1974 - ...altrimenti ci arrabbiamo! .... Cafe customer (uncredited as actor)
- Fantasma en el Oeste .... High roller in the casino (uncredited)
- Hold-Up, instantánea de una corrupción .... Photography shop proprietor (uncredited as actor)
1975 - No quiero perder la honra .... Priest (credited)
1976 - La muerte ronda a Mónica .... role unknown (credited)
- La petición .... Priest at party (uncredited as actor)
1977 - Casa Manchada .... Rich man (credited)
- Mi hija Hildegart .... Psychiatrist (credited)
- Secretos de alcoba .... Don Cornelio (credited)
- Uno del millón de muertos .... Priest (uncredited)
1979 - Historia de 'S' .... Hospital patient with porn (uncredited)
1980 - Cinco tenedores .... One of "Los Monteros" (credited)
- El español y los siete pecados capitales (TV series) Ep. 2: "La soberbia (segunda parte)" .... Father Abbot (credited)
1981 - Préstame tu mujer .... Priest at party (credited)
- Tú estás loco Briones .... Alvaro Mendez (uncredited)
- El embrujo de Sevilla (1931) EdCE (Enciclopedia del Cine Español)
- Falso noticiario (1933) EdCE
- Hola, Robinsón! (1959) EdCE
- Juego de niños (1959) EdCE
- Cotolay (1965) EdCE
- Crónica exterior (1976 short film) IMDb
- La verbena de la Paloma .... Costume designer
1937 - La reina mora .... Set decorator
1959 - La verbena de la Paloma .... Production designer
1960 - ¿Dónde vas triste de ti? .... Costume designer
- El indulto .... Costume and production designer
- Mi calle .... Costume and production designer
1961 - Fray Escoba .... Set decorator
- Julia y el celacanto .... Set decorator
1964 - Cyrano e d'Artagnan .... Set decorator
- La nueva Cenicienta .... Art director
- Los dinamiteros .... Set decorator
1965 - La visita que no tocó el timbre .... Set decorator
1966 - Tres perros locos, locos .... Set decorator
1967 - La casa de las mil muñecas .... Art director
- Mayores con reparos .... Set decorator
- Run Like a Thief .... Art director
1968 - The Face of Eve .... Set decorator
1969 - ¡¡Se armó el belén!! .... Production designer
- 99 Women …. Art director
- Honeymoon with a Stranger (TV movie) .... Art director
- Marquis de Sade: Justine .... Art director
- The Castle of Fu Manchu .... Production designer
1970 - Dramma della gelosia .... Set decorator
- El mesón del gitano .... Set decorator
- El último día de la guerra .... Art director
- Tibetana .... Art director
1971 - Varietés .... Set decorator
1972 - Che c'entriamo noi con la rivoluzione? .... Set decorator
- Dans la poussière du soleil .... Set decorator
- La semana del asesino .... Set decorator
- La ragazza di Via Condotti .... Production designer
- No encontré rosas para mi madre .... Set decorator
1973 - Las señoritas de mala compañía .... Set decorator
1974 - ...altrimenti ci arrabbiamo! .... Set decorator
- Hold-Up, instantánea de una corrupción .... Set decorator as "Santiago Ontanon Fernandez"
1976 - La petición .... Set decorator
1978 - Enigma rosso .... Set construction
- La traviesa molinera (1934) IMDb as Set decorator
- Los claveles (1936) EdCE as Director
- Una mujer en peligro (1936) IMDb as Set decorator
- Cain (1938) EdCE as Director
- La lunareja (1946) IMDb as Set decorator
- Una apuesta con Satanás (1948) IMDb as Set decorator and Screenwriter
- Nada menos que un arkángel (1960) IMDb as Set decorator
- Il gladiatore invincibile (1961) IMDb as Production designer. He is not credited in the English or German versions, but may be in the Spanish
- La rosa roja (1961) IMDb as Art director
- Madame Sans Gêne (1961) IMDb as Set decorator. Not credited in the French version but may be in the Spanish
- Cotolay (1965) IMDb as Costume designer
- El desastre de Annual (1970) IMDb as Art director
- Dieci bianchi uccisi da un piccolo indiano (1974) IMDb as Set decorator. Not credited in the Italian version but may be in the Spanish
- Comando al infierno (1969) IMDb as Production director. Not credited in the Spanish version