Who are the Daleks, and why are they the Doctor's most feared enemies?

The Daleks are a fictional extraterrestrial race of mutants in the British science fiction television series Doctor Who. They were created by writer Terry Nation and first appeared in the show's second season in 1963. The Daleks are known for their distinctive appearance and their catchphrase 'Exterminate!'

The Daleks are the Doctor's most feared enemies because they are a ruthless and powerful race bent on universal domination. They are also extremely difficult to defeat, as they are heavily armed and have powerful shields. Additionally, they are able to travel through time and space in their own spacecraft, which makes them a formidable opponent for the Doctor and his companions.

Throughout the history of Doctor Who, the Daleks have appeared in numerous episodes and have been responsible for some of the show's most iconic moments. Their popularity with audiences has ensured that they remain a major part of the series to this day.