Ryan Murphy, the creator of the hit drama series Glee, has revealed that he is considering introducing a new cast in the future.

The musical comedy drama, which is based in McKingley high-school focuses on its students and teachers. Murphy told Australia's Herald Sun that at some point the main stars will be too old to play high-school students.

He added that he introduced new characters such as Sam Evans in the second series to begin the transition.

"Every year we're going to populate a new group," he said. "There's nothing more depressing than a high schooler with a bald spot."

Murphy suggested that some of the original cast members may be leaving as early as 2012 and admitted it would be difficult to say goodbye.

"I think you have to be true to the fact that here is a group of people who come and go in these teachers' lives," he said. "They graduate and they're gone. When some of them finish their run at high school it will be very teary episodes. For me it will be particularly tough, but a new crop [of actors] will come in."

The Golden Globe winning writer said he had some concerns about how viewers would respond to new characters.

"[The current] kids caught on so quickly," he explained. "But I think one of the things I'm very happy we've been able to do this year is we've brought in new characters. I think if you keep regenerating - and I didn't think we could - I didn't know if people would want those characters [like Sam] - but they do."