What's wrong with donator?
Donor and donator both mean the same thing.
donor
noun
1. A person who donates something, especially money to charity
Synonyms
giver, contributor, benefactor, benefactress, subscriber, donator; supporter, backer, subsidizer, patron, sponsor; philanthropist
The only real difference is etymology.
Origin
Middle English: from Old French doneur, from Latin donator, from donare 'give'.
Origin
late 18th century: back-formation from donation.
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