Take a look at some of the monsters and villains Doctor Who has come up against both past and present.
The Cybermen are another of the Doctor's famous enemies. Only the Third, Eighth, Ninth and War Doctor never faced them. Their main aim is to try to convert all living life forms into Cybermen. Scary stuff!
Some of The Doctor's wackier enemies included The Kandy Man, who was made from sweets and who punished anyone who wasn't happy by drowning them in icing! Yikes! He was defeated by the Seventh Doctor, who discovered he could be stuck to the floor with lemonade!
The Weeping Angels are as old as the universe (or very nearly!) The Doctor describes them as "the deadliest, most powerful, most malevolent life-form ever produced." They feed on time energy and one touch from them could send you back to any point in history. They also move incredibly fast, but can't move when they are being looked at directly.
The Zygons have a rather unusual appearance. They look a bit like an octopus, however they are shape-shifters and can make themselves look like an exact replica of any living being! David Tennant has said that the Zygons are his favourite monsters from Doctor Who.
The Daleks are arguably one of Doctor Who's most fearsome foes. They're best known for their trademark phrase "EXTERMINATE!" and have been around since the first series of Doctor Who in 1963. They've remained The Doctor's greatest enemy ever since.
The Master is another Timelord - but also the Doctor's arch-nemesis. His goal is to rule the Universe and eliminate the Doctor. The Master has been played by a number of different actors since his first appearance in 1971, as he regenerates in a similar way to the Doctor.
The Daleks were created by Davros, the chief scientist of the Kaleds (an anagram of Daleks). Davros removed the Kaleds emotions and put them inside the super-strong Dalek armour, making them the terrifying nemesis they are today.
Sarah-Jane Smith and the Fourth Doctor are making a break from a Krynoid in "The Seeds of Doom". Krynoids are an alien species of plant life that look like giant pods.
The Silence are a group of aliens whose existence has remained a secret for thousands of years due to their ability to make people immediately forget them when they look away from them, but remember suggestions made to them by The Silence. Creepy!
"The Great Intelligence" is another of the Doctor's older enemies. It has no physical form and looks a bit like mist, but it took over these giant robot Yetis to fight against the second Doctor in 1967. The Great Intelligence made a return in the 2012 Christmas Special "The Snowmen" set in Victorian London.
The Ice Warriors are a group of reptilian warrior aliens from the planet Mars. They attempted to take over the Earth to escape their dying planet in a 1967 episode of Doctor Who, but were stopped by Patrick Troughton as the Second Doctor.
Here is a picture of the first generation of Cybermen that the first Doctor, actor William Hartnell, came up against in 1966.
Although normally a peaceful race who communicate through telepathy, The Ood turned hostile when their thoughts were taken over by "The Beast" in the episode called "The Impossible Planet".