George Roger Waters
Sort of ironically, it was Syd Barrett whose real first name was Roger.
Literary ones:
J.R.R. Tolkien
E.M. Forster
T.S. Eliot
F. Scott Fitzgerald
H.P. Lovecraft
C.J. Cherryh
H.D.
A political one:
(James) Harold Wilson
Musical:
J.J. Cale
P.P. Arnold
Not to mentionQ. (No, not the guy from Star Trek TNG.)
F. Murray Abraham, the actor.
L. Frank Baum
k.d. lang
(Peter) Overend Watts
H. G. Wells
I’ve got Adeline Virginia Woolf and Lafayette Ronald Hubbard. By the way, does the reason for dropping the name matter? Because I think a fair amount of these weren’t consciously dropped by the person, it was just that whatever their first name was was passed down through the generations so they needed a way to distinguish themselves from relatives (I’m thinking specifically of James Paul McCartney here, but chances are it applies to others - the whole multi-generational name thing was a lot more popular in the past than it is now).
Laura Reese Witherspoon
ETA
Patricia Rooney Mara
W. Michael Blumenthal.
E. Nesbit
B. Traven (except that his first name probably didn’t begin with a B, and his last name almost certainly wasn’t Traven - but nobody knows for sure).
P.D. James
R. Kelly
Gaius Julius Caesar
Jerome David Salinger
Edna Annie Proulx (who is now most often known as Annie Proulx but used to publish as E. A. Proulx and as E. Annie Proulx)
Edmund Clerihew Bentley
Always broke bad news gently.
“By the way, Trent old scout,
I was actually the one who took him out”.
Queen (Alexandrina) Victoria
King (Albert) Edward Vll
A. A. Milne
Hollywood:
Y. Frank Freedman. (That’s a very good question).
CCH Pounder (those are her initials, but she spells it without periods.
Authors
R. A. MacAvoy
C. L. Moore
Sports
R. A. Dickey
C.C. Sabathia
J. C. Martin
George Thomas “Tom” Seaver
Lynn Nolan Ryan
Lady Jayne Fonda - Not a title, Lady is her actual first name.
John William Ferrell
Thomas Jacob Black
You can’t mention Tolkien without mentioning his buddy C.S. (Clive Staples) Lewis.
In the literary world, there’s also Carson McCullers, née Lula Carson Smith.