Smallville's Jimmy Olsen reveal in season 8 was one of the show's worst ideas. At the end of the show's eighth season, Smallville killed Aaron Ashmore's Jimmy Olsen and dropped a shocking revelation about Jimmy that allowed the series to dispense with such an iconic character. Introduced in season 6, Jimmy was a photographer at the Daily Planet who became romantically involved with Clark's closest ally, Chloe (Allison Mack). The couple married in season 8. In the season 8 finale, Smallville shocked audiences by having Doomsday's human side, Davis Bloome (Sam Witwer), murder Jimmy Olsen — this was a bad idea on the part of the WB/CW show.
The twist came as a shock to viewers, considering that Jimmy was an integral part of Superman's story and one of only a handful characters who fans thought were safe. So how could Smallville get away with killing off such an important character before Clark even became Superman? This was explained at Jimmy's funeral when Chloe handed off his camera to a young boy and it was revealed that "Jimmy" was only his middle name. Apparently, Smallville never killed off Jimmy Olsen at all.
It was certainly a shocking reveal that no one saw coming, but that doesn't mean it was a good idea. Over the course of three seasons, Smallville had developed Aaron Ashmore's character into a comic book accurate version of Superman's Pal, complete with his interest in photography, good-natured personality and habit of referring to Clark as "C.K." There was no reason to suspect that Ashmore's character was anyone but Jimmy Olsen. That's why it was so hard to believe that the young boy in the finale would grow up to use the same name, get the same job at the same newspaper, and adopt the same friendship with Clark as the older Jimmy.
Later, a trip to the future confirms that his adult self is also played by Aaron Ashmore. What this all means is that the two are essentially the same character, and the only thing that sets them apart is the difference of approximately ten years. While this twist was able to help Smallville succeed in delivering one of its biggest and most unexpected deaths, its unfortunately hurt by the fact that it doesn't make a whole lot of sense.
The need for the twist highlights a major problem that comes with prequels. Using characters with predetermined futures can make it rather challenging to surprise the audience. This situation forces shows to either stick to the status quo, avoid using the character, or break the rules. Smallville tried a unique approach to get around these issues, but in the case of Jimmy Olsen, it just didn't work.