Bill Cosby's daughter, Ensa, who steadfastly supported her dad through his legal troubles, has died ... TMZ has learned.

The 44-year-old died Friday night in Massachusetts ... sources tell TMZ.

Ensa was always in her dad's corner, releasing a statement last year, "My father has been publicly lynched in the media and my family, my young daughter, my young niece and nephew have had to stand helplessly by and watch the double standard or pretending to protect the rights of some but ignoring the rights of others."