Otto Mellies, born January 19, 1931, in Stolp in Western Pomerania, attended actor's training at the theatre in Schwerin under impresario Lucie Höflich from 1947 to 1949. His brother Eberhard also pursued a career in acting. After performing at theatres in Neustrelitz, Stralsund, Rostock, and Erfurt, artistic director Wolfgang Langhoff brought Mellies to Deutsches Theater Berlin. Mellies is a cast member of the theatre to date.

Mellies made his debut in front of the camera in a supporting role in Franz Barrenstein's entertainment movie "Sommerliebe" (1955), a role that was followed by appearances in Martin Hellberg's literary adaptation "Kabale und Liebe" ("Intrigue and Love", 1959), in the film version of Jacques Offenbach's operetta "Die schöne Lurette" (1960), directed by Gottfried Kolditz, and in "Minna von Barnhelm oder das Soldatenglück" (1962), again directed by Martin Hellberg. Besides these adaptations of classic plays and other film versions of theatre plays, Otto Mellies also starred in contemporary films, for instance, as German worker Erich in Gottfried Kolditz's "Simplon-Tunnel" (1959). Against the backdrop of the construction of a railroad line between Switzerland and Italy, Erich's love to the Italian Rosa sparks a quarrel with an Italian worker. In "Der Arzt von Bothenow" (1961), directed by Johannes Knittel, Mellies played a young, successful physician in Berlin who has to leave his workplace in the large city because of a severe medical malpractice. In the provincial town of Bothenow, he tries to dismiss his sophisticated lifestyle and to straighten out his life again.

Mellies made his debut on the TV screen with his performance in the role of the title character in "Dr. Schlüter" (1965), directed by Achim Hübner. Furthermore, with this performance he also became known beyond GDR borders. In the popular five-part movie, he portrayed a career-obsessed chemist who is asked by his father-in-law, the industrialist Vahlberg, to take over the chemical plant of a concentration camp in Poland at the beginning of World War II. But he decides to flee and does not return to Germany for several years.

Since the 1970s, Otto Mellies has mainly performed on stage, appeared in several TV shows, and also worked as a dubbing voice. He is the German voice of actors like Paul Newman, Christopher Lee, and Sean Connery. Furthermore, the actor who lives in Berlin lends his voice to radio plays and performs at readings. In 2006, Mellies celebrated his 50th stage anniversary at Deutsches Theater Berlin.

One year later he appeared in the successful feature film "Frei nach Plan" ("According to the Plan") by Franziska Meletzky, which won the Jin Jue Award in the category "Best Film" at the 10th Shanghai International Film Festival. In 2012 Mellies was awarded the German Film Prize as Best Supporting Actor for his role as the father of the fatally ill protagonist in Andreas Dresen's "Halt auf freier Strecke" (2011).

In Kilian Riedhof's "Sein letztes Rennen" (2013) he played at the side of Dieter Hallervorden, in Roland Suso Richter's TV-docudrama "Die Spiegel-Affäre" (2014) he had an appearance as Konrad Adenauer, in the celebrated "Tatort: Im Schmerz geboren", directed by Florian Schwarz, he also played a supporting role. His last film appearance was as an embittered former GDR judge in the Berlin "Tatort" episode "Das Leben nach dem Tod" (2019).

Otto Mellies died on 26 April 2020 at the age of 89.