3) Bruce Wayne
On the subject of Smallville, it wasn’t always the plan to create a series revolving around the teenage years of Clark Kent. The project initially began as a prequel for Superman’s fellow Justice Leaguer, Batman.
In 1999, The WB were very excited for Bruce Wayne, which would have followed the rich orphan as a teenager, as he began the journey to Batmanhood. The plan was for it to be a Buffy The Vampire Slayer-type show that could run for five or six seasons, and Shawn Ashmore (later Iceman in the X-Men films) was apparently considered to play Bruce. Regardless of whether it would have been any good or not, it certainly would have been the most in-depth exploration of the character’s origins we had seen on screen up to that point.
However, Warner Bros.’ film arm eventually nixed the idea, as they were planning a similarly-themed Batman: Year One movie at the time. Ah, well.