Ryan O'Neal -- Don't Forget About FARRAH FAWCETT!!!

Three years ago today, the world mourned the death of Farrah Fawcett ... for about 5 minutes ... until Michael Jackson died ... and overshadowed the loss of Charlie's most famous Angel.

But today, Farrah's baby daddy Ryan O'Neal honored her memory with a shirt featuring the TV icon ... who passed away after a long battle with anal cancer.

The image on the shirt is Farrah's most famous photo -- taken in 1976 -- and went on to become one of the best selling posters in history.

Farrah was 62 years old.