used when you are telling someone something that they probably know or expect:
Needless to say, any contributions of money will be gratefully received.
needless troubles, suffering, loss etc are unnecessary because they could easily have been avoided [= unnecessary]:
The report caused needless anxiety to women who have attended the clinic.
We need to bring to an end these needless deaths.
Charles hates needless waste.
People are dying needlessly every year of heart attacks.