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. Even when he's not outright losing, he's getting in over his head and coming to the Doctor for help. So 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 Nyssa's father, uses Logopolis to destroy a section of the universe and hold the rest to ransom, and finally gets to kill the Doctor by knocking him off a big satellite dish!
In other words, the Master basically gets everything he's ever wanted: a nifty new body, the death of his greatest enemy, and the universe in the palm of his hands. Nobody's laughing at him now, are they?
Inevitably though he fumbles things by reaching beyond his grasp when he kidnaps Adric and builds Castrovalva, but that's hubris for you.