David Letterman Looks More Like Joaquin Phoenix Now

David Letterman the late night host is no more -- replaced by someone who looks a lot more like Joaquin Phoenix from back in the day.

The 68-year-old already is getting more unrecognizable by the day. He's down in St. Barts sporting a new bald and even bushier bearded look.

If any ZZ Top cover bands are hiring in the Caribbean ... get Dave a guitar.