I think there's some computer scientist (or similar) whose given name is just R, I forget what their last name is though.

And apparently Johnny Cash was born J. R. Cash.

From Wikipedia:

His mother wanted to name him John and his father preferred to name him Ray, so J. R. ended up being the only compromise they could agree on. When Cash enlisted in the Air Force, he was not permitted to use initials as a first name, so he changed it to John R. Cash. In 1955, when signing with Sun Records, he started using the name Johnny Cash.

Just like Harry S Truman "Since the S did not stand for a name, Harry didn't use a period after it for most of his life."

https://www.trumanlittlewhitehouse.com/key-west/president-tr...

Similarly Oppenheimer, of the Manhattan project

He thought assuming that leading J made him seem more posh and WASPy

Interesting story, but, unfortunately, it's not true. Wiki gives his full name as "Julius Robert Oppenheimer." Julius was apparently his father's name as well.

https://en.wikipedia.org/wiki/J._Robert_Oppenheimer

"E" can also be a surname or given name in Chinese. It's pronounced like "uh" in English.

https://en.wikipedia.org/wiki/E_(surname) https://en.wikipedia.org/wiki/Cai_E