Patrick McGoohan played both John Drake and Number Six. "John Drake" was the main character in Danger Man ( Secret Agent) and "Number Six" in the Prisoner. It is debated back and forth if John Drake is Number Six. Patrick McGoohan claimed they were different, but many people who worked with him on The Prisoner believe they are the same person.
It is confirmed that the premise of the Prisoner could of only have come from Secret Agent because it was a secret agent retiring and what happens after words? Assuming John Drake is the Prisoner is safe and superficial. It is also possible that Number Six became something completely different from John Drake, even if John Drake inspired him.
It is also believed since McGoohan did not own rights to John Drake he denied the relationship, in the comic book sequel of The Prisoner, Number Six is referred to as "John White" when in Canada. John White was a name John Drake used in Danger Man. This can be seen as an additional tie between the two characters of John Drake and Number Six. With Patrick McGoohan's death this question can never be answered. Is John Drake Number Six?