I remembered an interview a while back with Vince Gilligan talking about how Bryan Cranston's guest role in an X Files episode solidified him for the role of Walter White on Breaking Bad and went to check it out. I was surprised to find that Aaron Paul appeared in an episode as well. It gets even better! 59 seconds into the video you see someone who looks strangely familiar. Is that Jesse Plemons, aka Todd?! IMDB turned up nothing, but it's possible he could've been uncredited for the role. Dean Norris even appeared on season 2 episode 22 (pictured above).
I was on a hot streak, so I went for the money and typed in RJ Mitte... and turned up an uncredited Hannah Montana appearance?! Mitte was even romantically involved with Miley Cyrus at one point. As Walt Jr. would say, "THIS IS BULLS***!" Watch the videos below.