Ominous and epic, Anthony Isaac's composition for the original Terry Nation series of Survivors perfectly set the scene for a show about a pandemic wiping out all but 1% of the population.
Like a lot of great theme tunes this was also accompanied by a great credit sequence, which you can see below. A cack handed Chinese scientist drop a test tube full of a lethal chemical. Said scientist then flies out to Russia, collapses and dies, and the virus has gone global, as depicted by the stamps in a montage of passports.
The remake of the show in 2008 also had quite a strong theme tune from Edmund Butt, but as good as it is, its somehow less iconic than the original