The actress has taken a number of film and TV roles since leaving the sci-fi show, but it remains her most famous achievement.
Her fears were confirmed at a speech she gave in England.
She says, "Last year I went to talk to the Cambridge University's Students' Union.
"All they wanted to ask me was about X Files. After a while thought: 'Have they got nothing else to talk about?' But then I realised, I haven't done anything else."