According to Deadline, two of the regulars for Star Trek Discovery will be leaving the series at the end of season two. Anson Mount joined the cast for season two as Captain Christopher Pike of the USS Enterprise. Rebecca Romijn joined as Pike’s second in command, Number One. They were only under contract for this season only.
Their characters was used for this season’s overarching run. This was used to sync up the series to the original Star Trek cannon of events. Season 2 has now wrapped filming.