No one has a better Cinderella story than Lawler. He was irrellevant, and a little over a year later, he was champion.
Hunt could have, but unfortunately he just didn't win his big fights. He gets an honorable mention for being tied for longest losing streak, then coming back to be in title contention.
Chael Sonnen should probably get a mention too. Before he fought Anderson, he was just some mediocre WEC acquisition. He beat 2 highly rated contenders to earn his shot, and almost beat the P4P #1 fighter in the world. He became the best selling UFC fighter after that. His fall from grace is almost as noteworthy because of how high he climbed.