‘Let’s Kill Hitler’ was the seventh episode of the sixth season and it was the comeback episode after a mid-season break. Yet it was a case of wasted potential.

The episode picked up after the excellent ‘A Good Man Goes to War’ and shows River Song’s first encounter with The Doctor since her timeline and The Doctor’s are incredibly convoluted. What should have been a great moment for the two of them was a huge disappointment. It was revealed that before River Song took the form of Alex Kingsbury she was one of Amy and Rory’s school friends and ends up traveling back to Nazi Germany.

After the epic events of ‘A Good Man Goes to War’ great things were set to come – revealing River Song was really Amy and Rory’s daughter and an early form of a Time Lord. Instead ‘Let’s Kill Hitler’ went for a lighter, comedic tone and shortcut what was set up before, River Song being abducted as a baby and raised to assassinate The Doctor.

It was River Song’s weakest episode.

‘Sleep No More’ was Doctor Who‘s attempt at a found-footage episode – a sci-fi horror story about humanity being able to combat the need for sleep but ends up creating monsters that target people. The episode had a solid nugget of an idea: it could have been made into an interesting psychological horror and could have used the theme that humanity shouldn’t fight certain natural processes. The episode ruins this by making the monsters living eye gunk, making them ridiculous rather than scary. The episode also couldn’t override the found-footage gimmick even if it uses the Chronicle style where every camera was used instead of one camera.

The episode did have an excellent end where the man narrating the story was really a sleep monster and it serves as an intriguing hook for its sequel episode.

For a long time ‘Love and Monsters’ was the most hated Doctor Who episode from the modern era and it is an episode with a lot of problems. ‘Love and Monsters’ was the first ‘Doctor-lite’ episode – one where The Doctor and his companion have reduced screentime. This idea had two functions, the first to tell stories from different perspectives, the second is budgetary because it allows Doctor Who to film two episodes at the same time.

‘Love and Monsters’ had a strong idea behind it: it focused on people who had met The Doctor and left such an impact on their lives that they try to find him again. What this episode did with the concept was the people ended up forming a band. The episode had recognizable British actors like Marc Warren, Shirley Henderson, and Peter Kay and it was a real waste of talent.

The monster in the episode was the Abzorbaloff and it was designed by a 9-year-old who won a contest. The concept he came up was sound – it was a monster that absorbs people into his body and was meant to be the size of a bus. What we got was a joke character with one unfortunate person whose fate is that their face ends up next to his anus.

To put this episode in perspective it ends on an oral sex joke.

Episodes like ‘Sleep No More’ and ‘Love and Monsters’ can at least be described as good ideas that were poorly executed. That defense cannot be said for the final two episodes on this list – starting with the tenth episode of the eighth season ‘In the Forest of the Night.’ What happens in this episode is trees suddenly grow all over the world, including in Central London where Clara and Danny Pink were taking a group of children on a field trip with the more ‘challenging’ children getting separated from the group: fortunately The Doctor is to escort the children to safety whilst also doing what he does best – save the world.

‘In the Forest of the Night’ which was clearly designed to be a lighter hearted, more family episode, yet came up with one of the silliest ideas possible – that the sudden tree growth was nature’s way to defend the planet from a solar flare. Even for Doctor Who‘s – whose science can be dubious – this was a stretch, coming across as a combination of M. Night Shyamalan’s The Happening and the ‘Xmas’ segment from the Futurama episode ‘The Futurama Holiday Spectacular’.

Even for people who can look pass the dodgy science, the episode had little in the way of urgency despite the world threatening stakes and came off as overly sentimental due to The Doctor trying to bond with the children including a girl mute who went mute after a family tragedy.

It had to be a season eight episode that has the unwanted honor of being the worst modern Doctor Who and ‘Kill the Moon’ is one of the most derided episodes. ‘Kill the Moon’ can be summed up in five words: ‘the Moon is an egg.’ That is the concept of the episode: the moon is an egg that’s about to hatch, causing environmental destruction on Earth. The idea is bad enough and it is made worst when The Doctor leaves Clara, one of her students and an astronaut, to make the decision on whether to kill the hatching or let it live. The episode ends on cop out when The Doctor reveals that animals that hatch from eggs do not destroy their own nest which means Earth was always safe. It’s Doctor Who at its very worst.