People who want to declare their religion as "Jedi" or call themselves witches will still be able to do so in the 2011 Census, its director has said.
In 2001 - the first time the questionnaire contained a voluntary question about faith - almost 400,000 people claimed they were members of the Star Wars movement.
Glen Watson, the Office for National Statistics (ONS) Census Director, said although putting joke responses on the national survey form was "not an acceptable thing to do", it could not be stopped.
Speaking at the launch of the advertising campaign for the £482 million information-gathering exercise, he said: "The religion question is the only voluntary question on the whole questionnaire.
"We would process the information and we would include that in the results, I imagine.
"I don't think we would pursue somebody for declaring their religion, for example, as Jedi.
"As I say, it's a voluntary question. I'm not really saying that we can stop it.
"If people really want to express their religious affiliation in a particular way, they're within their rights to do so."
Since the last census, the use of social networking websites such as Facebook and Twitter has rocketed and campaigners have used them as tools to galvanise support for various movements.
In 2009, a Facebook campaign led to the rock group Rage Against the Machine taking the Christmas chart number one spot ahead of X Factor winner Joe McElderry in a grass-roots plot apparently aimed against Simon Cowell.