He is mainly known in Germany as the first host of the ZDF Hitparade, a monthly music show in German TV which ran several decades and became an institution. I connect no nostalgia with that show because it was conservative and mainstream and not much interesting happend there. So I wouldn't lose any words about Heck if he was not dabbling in acting too and had at least two interesting role choices in his career. Unlike with many other German actors particular in the 70s, money can't be the trigger, he came from a whealthy family and moderating a top ranking monthly TV show should also result in a tolarable paycheck.
The first noteworthy movie is the controversial TV experiment Das Millionenspiel from 1970. Wolfgang Menge, who also wrote the satirical Ein Herz Und Eine Seele, adapted the story The Prize Of Peril by Robert Sheckley to a realistic German TV show where the candidate has to run away from some killers and survive a week. Only briefly in the beginning it was announced that the whole show was fictive and many watchers who zapped in later were shocked, taking it for real. But worse, many applied to be either the next candidate or member of the killer gang. Dieter Thomas Heck basically played himself, the host of the show, moderating the live inserts from the escape and interviews with involved people and lend so realism to the show. This could easily be a career ender but it didn't harmed him. The at that time for most TV watchers unknown political cabaret artist Dieter Hallervorden played one of the killers, a couple of years later he eventually became TV regular with his slapstick shows. Das Millionenspiel wasn't shown for decades on TV but not because of its controversy, main reason was a despute about the rights. In France Yves Boisset turned Sheckleys story 1982 into the movie Le Prix Du Danger with Michel Piccoli.
The other movie is the lesser known Pankow '95 by Gábor Altorjay, a dark satire from 1983. Set in the near future in a still divided Germany, Udo Kier plays an inmate of a mental institution in east Germany. His character is a scientist who lost his mind when he discoverd after he fed all available data into a computer, that the world is soon about to end. Another inmate is a green skinned test tube born man who wants to go back into a womb to stage actually a real birth. (Regular listeners to my music might found this sounding familiar and indeed, that movie was the inspiration for at least 4 lyrics for Notstandskomitee in its classical phase, inclusive 'Gebärmutter'). Dieter Thomas Heck plays the director of the institution and even has the chance to demonstrate an anatomic feature he had and confirmed in a talkshow: he was able to stick his earlobes in his ears in real life, maybe that helped through the Hitparade years. Amoung the cast in this little, rare gem were Christine Kaufmann, Magdalena Montezuma and Nina Hagen.