10 Doctor Who Episodes Where Evil Won
8. Logopolis
From his very first appearance in Terror of the Autons, the Master was always on a losing streak. When he's not outright losing, he's getting in over his head and coming to the Doctor for help. Is it any wonder that, in The Mind of Evil, we learn that the Master is absolutely terrified of the Doctor laughing at him?
However, from The Keeper of Traken to midway through Castrovalva, the Master is on a bit of a roll. He gets a new body by possessing that of Nyssa's father, Tremas. Then he uses Logopolis to destroy a quarter of the universe and hold the rest of it to the ransom, before finally getting to kill the Doctor by knocking him off a big satellite dish!
Quite simply, the Master basically gets everything he's ever wanted in Logopolis; nifty new body, death of his nemesis, and the universe in the palm of his hands. Nobody's laughing at him now, are they?
Inevitably, he fumbles things by reaching beyond his grasp by kidnapping Adric and building Castrovalva, but that's hubris for you.