No biographical details are currently known other than that he worked equally as a model and actor.
IMDb and other sites have him listed as "Ricardo G. Lilló", but he was credited far more frequently without the initial, so that's the spelling I have opted to use. I already had him saved in a number of uncredited generico-type roles before finding his identity, only one of which matched with the 63 roles listed by IMDb, so I am optimistic that he will have a substantial number of undocumented background roles to be found.
He does have 5 credited roles where he is unidentified with no obvious explanation, not altogether unusual with Spanish actors - it might be that there is another actor by the same name, but it is not such a high volume of titles that this is by any means certain.
- Las chicas de la Cruz Roja .... Man in the street (uncredited)
1959 - Carmen la de Ronda .... Party guest (uncredited)
- De espaldas a la puerta .... Nightclub customer (uncredited)
- La vida alrededor .... Business partner (uncredited)
- Los tramposos .... Executive at the meeting (uncredited)
1960 - ¡Ahí va otro recluta! .... Military commander (credited)
- Alfonso XII y María Cristina ¿Dónde vas triste de tí? .... Member of parliament (uncredited)
- Ama Rosa .... Party guest (uncredited)
- Días de feria .... Cafe customer (uncredited)
- La corista .... Nightclub customer / Theatre audience member (uncredited)
- Mi último tango .... Gigolo on the ship (uncredited)
- Un ángel tuvo la culpa .... Party guest (uncredited)
- Un rayo de luz .... Man from the embassy (credited as "Ricardo G. Lillo")
- Un trono para Cristy .... Guest at the ball (uncredited)
- Una chica de Chicago .... Plane passenger (uncredited)
1961 - Adiós, Mimí Pompón .... Suitor of Mimi (credited)
- Armas contra la ley .... Reporter (credited)
- El pobre García .... Barber (credited as "Ricardo Garcia Lillo")
- Fray Escoba .... Luis Fernandez de Bocadilla (credited)
- La bella Mimí .... Friend of Mimi (credited)
- Pecado de amor .... Police officer (uncredited)
- Ursus .... Priest of Zaas (uncredited)
1962 - Arrivano i titani .... Advisor to Cadmos (uncredited)
- Escuela de seductoras .... Chairman of the conference (uncredited)
- Martes y trece .... Guest of Franz (credited)
- Rosa de Lima .... Viceroy of Peru (credited)
- Teresa de Jesús .... Man visiting nuns (credited as "Ricardo Gª Lillo")
- Tú y yo somos tres .... Office worker in the window (uncredited)
1963 - 55 Days at Peking .... Guest at the ball (uncredited)
- El sabor de la venganza .... Hotel clerk (credited)
- Eva 63 .... Actor in ad shoot (credited)
- La fuente mágica .... American businessman (credited)
- La pandilla de los once .... Man chatting up Dick's girl (credited as "Ricardo Gª Lillo")
- Operación Embajada .... Man in the club (credited)
- Perro golfo .... Embassy doorman (uncredited)
- Una chica casi formal .... Luis (credited)
1964 - Búsqueme a esa chica .... Old friend of Johnny (uncredited)
- El espontáneo .... Hotel manager (credited)
- El extraño viaje .... Prospective tenant (credited as "Ricardo G. Lillo")
- El salario del crimen .... Señor Alreda (credited)
- El Zorro cabalga otra vez .... Colonel (credited)
- Gli eroi di Fort Worth .... (credited, but not found)
- I promessi sposi .... Nobleman (uncredited)
- Rueda de sospechosos .... Night porter (uncredited)
- Saul e David .... (credited, but not found)
- Un balcón sobre el infierno .... Friend of Sartori (credited)
1965 - Amador .... Man in church (credited)
- Aventuras del Oeste .... Majors (credited)
- Doctor Zhivago .... Guest at the ball (uncredited)
- El mundo sigue .... Anselmo (credited)
- Jandro .... Bank executive (credited)
- La carga de la policía montada .... Doctor (credited)
- Megatón Ye-Ye .... Director (credited)
- Mi canción es para ti .... Nightclub emcee (credited)
- Secuestro en la ciudad .... Friend of Ignacio (credited as "Ricardo G. Lillo")
- Uncas, el fin de una raza .... Captain Pitt (uncredited)
1966 - Baile en capitanía (TV movie) .... General Rada (credited - uncertain identification)
- Cartas boca arriba .... Chairman of the board (uncredited)
- Diego de Acevedo (TV movie) .... (credited as "Ricardo Gª Lillo", but not found)
- El arte de no casarse .... Patro's employer (uncredited)
- El misterioso señor Van Eyck .... Boat owner (credited as "Riccardo Lillo")
- Mestizo .... Commander (credited)
1967 - Dossier Mata Hari (TV mini-series) Ep. 3 .... Lovelace (credit unknown)
- El hombre que mató a Billy el Niño (...e divenne il più spietato bandito del sud) .... Lincoln landowner (uncredited)
- Historias para no dormir (TV series) Ep.: "El cuervo" .... Waiter (credited)
- La familia Colón (TV series) Ep. 10: "A Elena le sienta bien el luto" .... Agustin (credited as "Ricardo Garcia Lillo")
1968 - Bonaparte quiere vivir tranquilo (TV movie) .... (credited, but not found)
- La escala rota (TV movie) .... Waiter (credited)
- Nunca es tarde (TV movie) .... Man delivering flowers (credited)
1969 - Prisionero en la ciudad .... Man who rejects the chicken (credited)
1970 - Arriva Sabata! .... Bank manager (credited)
1971 - El apartamento de la tentación .... (credited, but not found)
- Nicholas and Alexandra .... Man at Karensky's war conference (uncredited)
- Visto para sentencia (TV series) Ep. 10: "The Nice Death (La deliciosa muerte)" .... Mr. Roberts (credited)
1972 - Alta tensión .... Party guest (credited)
- Che c'entriamo noi con la rivoluzione? .... Member of the theatre troupe (credited)
- La banda J. & S. – Cronaca criminale del Far West .... Preacher (credited)
1973 - El juego del adulterio .... Hotel receptionist (credited)
1974 - Juan y Manuela (TV series) Eps. 5, 10, 11, 13 .... The Count (credited)
- Onofre .... Catwalk model (uncredited)
1975 - Il bianco il giallo il nero .... Prisoner (uncredited)
- Tres suecas para tres Rodríguez .... Don Enrique (credited)
1976 - Adulterio a la española .... Dinner companion (credited)
- El anacoreta .... Lillo (credited)
- Ligeramente viudas .... Accident victim (credited)
- Sábado, chica, motel ¡qué lío aquel! .... role unknown (credited)
1977 - Curro Jiménez (TV series) Ep. 3: "20.000 onzas mejicanas" .... role unknown (credited)
1979 - Historia de 'S' .... Guest at the show (credited)
- Mi adúltero esposo .... role unknown (credited)
1992 - Prisioneras del terror (TV movie) .... Laura's father (credited)
- La notte è fatta per… rubare, aka Aquí robamos todos (1967) EdCE.
- El paraíso ortopédico (1969 short film) IMDb
- El Séneca (1970 TV series) Ep.: "El Séneca, los moros y los cristianos". IMDb as First socio (which has a number of translations)
- Música y estrellas (1976 TV series) IMDb has Ricardo listed as appearing in 8 of 10 episodes, but with no indication of what capacity he appears in. There is a token episode on RTVE which I checked, but could not see Ricardo, who was not credited.
- Las locuras de Jane (1978) IMDb
- Il ponte dei sospiri (1964) IMDb with no role. Ricardo is not credited, at least not in the Italian version, and does not appear as far as I could find.