Lois Lane
Erica Duranc was a recurring guest in season four, before she became a series regular. Producers wanted to bring Lois Lane into the series, and with Chloe’s supposed death in the season three finale, they saw an opportunity. Additionally Durance was cast just three days before filming began. Initially she could only appear in four episodes, however after negotiations her character was allowed to have more appearances. Good choice!
Jimmy Olsen
Aaron Ashmore portrayed Jimmy Olsen, and in season six he was just a recurring guest before becoming a regular cast member from season seven. Ashmore said his casting was a surprise, “I auditioned for [the role] and I put myself on tape. I hadn’t heard anything, and a couple of weeks later, all of the sudden, I got the call saying, ‘You’re going to Vancouver to start shooting Smallville.’ It’s a dream come true, really.”