Noun
megadonor (plural megadonors)
Someone who donates a lot, or who is responsible for a large amount of the donations flowing to a person or entity.
The self-proclaimed "elite strike force" also alleged that the machines were financed by the Clinton Foundation and Democratic megadonor George Soros. Source: Internet
It was founded with a $500,000 assist from the conservative megadonor Mercer family. Source: Internet