the American, Richard Hoaglan

[Vladv1]

"The best-known writer and researcher on this subject is the American, Richard Hoagland, a science journalist and a former adviser at the NASA Goddard Space Flight Center".
David Icke, Children Of The Matrix.

Explain please the use of comma before Richard.
I would say "The best-known writer and researcher on this subject is the American Richard Hoagland, a science journalist and a former adviser at the NASA Goddard Space Flight Center".

 

[probus]

Both your version and Icke's are correct. I think the omission of commas in such cases is now more common and more modern than their use.