Buck Rogers in the 25th Century (1979)

S2E6 Mark of the Saurian

The Saurians devise a scheme to annihilate the Searcher and ignite a war across the galaxy by disguising themselves as humans to infiltrate the starship and a nearby space station. Buck, who has fallen ill with a peculiar virus, is the only one able to perceive the Saurians’ true appearance, but his warnings go unheeded. As the Saurians recognize Buck as a danger to their plans, they turn their focus to eliminating him, launching several attempts on his life.