The actor was promoting the mockumentary 'I'm Still Here' when he delivered one of the strangest interviews ever recorded for late night television.

He appeared in character for his Casey Affleck-helmed mockumentary 'I'm Still Here', which saw Phoenix quitting acting to pursue a hip-hop career.

J oker star Joaquin Phoenix recently returned to The Late Show after a whopping 15 years — but something else also happened: he apologized for his infamous David Letterman interview from 2009 that took place on the show before Letterman turned the reins over to Stephen Colbert.