Astral Light - The person on Megadeth’s “The World Needs A Hero” album cover is Donald Marshall. It's a painting of Donald Marshall's clone at the cloning centers. It’s an example of what Donald Marshall looks-like after being clone tortured/killed at the cloning centers.
The picture on the left is Donald Marshall (real body) and the picture on the right is a painting of Donald Marshall (clone body).
Donald Marshall wanted Dave Mustaine/Megadeth to put him on the cover because he wanted to use it as a reference in the future, if the Illuminati ever decided to release his clone memories (which they did at age 30).
Donald Marshall On Megadeth's "The World Needs A Hero" Album Cover (Extended Ver.)