The question has been around for a long time and it appears that some of you may have missed the information when I first published it.
Here it is again:
Larger version:
What is Prince Charles’ blood type?
When donating blood in the 1980s, the world learned that Prince Charles is a universal donor (O negative). Source: https://www.rhesusnegative.net/staynegative/prince-charles-o-negative/