donator

1. donor; benefactor
   Novu opremu za bolnicu kupio je jedan donator. — A donor bought the new equipment for the hospital.
   Festival finansiraju donatori. — Donors fund the festival.
2. (in medicine, less common) donor
   Pronašli su odgovarajućeg donatora bubrega. — They found a suitable kidney donor.

In medicine the usual terms are donor (donor organa, donor bubrega) and davalac (davalac krvi); donator is less common in this sense and mostly refers to someone who donates money or goods.