Over the year, Dexter Morgan has squared off against an ice truck killer; a detective that learned his secret; an ambitious, shady lawyer; and a serial-killer family man.

But the title character of Showtime's Dexter will face a new foe on season five, as teased in the poster below: his own guilty conscience, which is a result of Rita's gruesome murder.

The drama returns with new episodes on September 26. Visit our Dexter spoilers section for more insight on what's to come.

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.