One of the driving mysteries of Smallville was Clark Kent's secret powers and alien identity. There were those who knew and were sworn to secrecy. Then, there were those who knew or wanted to know, and it didn't end well for them. Those unfortunate characters were largely minor and one-off characters in the series. Among the main characters, however, the knowledge of Clark's secret and the potential strain on their relationship from knowing made the reveal either heartwarming or heartbreaking.