by the very wonderful, they might be giants.

the only song about the 11th president of the USA.

on Primus' Frizzle Fry album

I assume it's a person's name, and not a real person.

A song by REM.

Real person - though I doubt it is his real name.

Same goes for Bo Diddley by Bo Diddley.

John Mellencamp did a song called John Cockers which does not mention that name anywhere in the song.

Eleanor Rigby?

The song Joan Baez sung at Woodstock.
I beleive he coined the phrase "Pie in the sky" to satirise religion. He was not a popular person. Framed for murder and executed I think.

Billy Austin, by Steve Earle. A death row song, not sure if the name is fictional.
Sally Simpson, by The Who.
Marie Provost, Nick Lowe. Real person, name misspelt.
Alicia Ross, by Kathleen Edwards. Real person.
Faron Young, by Prefab Sprout. Also a real person.

If you look under "trad.arr." there are many more examples, such as:
Matty Groves (Fairport)
Annachie Gordon (Nic Jones)

Kevin Carter (manics)
Nathan Jones (Supremes)
Sam Jones (Richard Thompson)

John Lee by Fairport Convention, the "title" track, I guess, of an entire LP based on the life and times of John Babbacombe Lee, hung unsuccessfully 3 times, therefore having to be freed.

John Wesley Hardin(g)
Hattie Carroll
George Jackson

Sally Cinnamon (the Stone Roses)
Maggie May (Rod Stewart)
Bob Lind (Pulp)
Faron Young (Prefab Sprout. Which is on the Steve McQueen album - that's got to be worth double points)

Janie Jones - The Clash

(he's a weatherman, you know)

had his fair share of song titles - check out the list and his story here: http://en.wikipedia.org/wiki/Casey_jones

Jack Straw (Grateful Dead)
Johnny (B) Goode

Lambchop - Steve McQueen, Timothy B. Schmidt, D. Scott Parsley, Gloria Leonard
Sun Kil Moon's first album has songs called Glenn Tipton, Salvador Sanchez and Duk Koo Kim.
Sufjan Stevens - Adlai Stevenson, Saul Bellow, John Wayne Gacy Jr
Pixies - Alec Eiffel

Not on any recording*, but a live favourite, Alexander Graham Bell.

Alexander Graham Bell
Written by Richard Thompson Appears on "RT" Disc 5 - Real Rarities (2006)
Miscellaneous Songs (9999)

"Alexander Graham Bell
Note the name and note it well
Father of the modern age
His inventions are all the rage
Of course there was the telephone
He’d be famous for that alone
But there’s 50 other things as well
From Alexander Graham Bell

Edison had cylinders
But Bell made records flat
Which we remember gratefully
When we play our floppy or CD
Of course there was the telephone
He’d be famous for that alone
But there’s 50 other things as well
From Alexander Graham Bell

Born in Scotland, moved away
To Canada and the USA
Studied speech, took a wife
Helped the deaf all his life
Came up with a threshing machine
Before he made it to a teen
After years of sweat and toil
He invented the hydrofoil

The respirator was his chance
To save his baby’s life
And just like the Brothers Wright
He got heavily into flight
Of course there was the telephone
He’d be famous for that alone
But there’s 50 other things as well
From Alexander Graham Bell

Graham Bell, Alexander,
It is tantamount to slander
To call him just a scientist
Why his inventions top the list
Edison, he was a thief
And Tesla nuts beyond belief
But Alexander was a gent
So philanthropic, so well meant

Founded Science Magazine
Wrote a book for kids
Because he was a caring fellow
Gave a hand to Helen Keller
Of course there was the telephone
He’d be famous for that alone
But there’s 50 other things as well
From Alexander Graham Bell

Alexander Bell, Graham
Modern life would sure be mayhem
Without tetrahedral cells
X-rays, faxes, decibels
I think I’d say, and it’s no fiction
Without fear of contradiction
He improved our lot a smidgeon
From the age of carrier pigeon

Television was a thing
That he had all prepared
But he left that to his pupil
John Logie Baird
Of course there was the telephone
He’d be famous for that alone
But there’s 50 other things as well
From Alexander Graham Bell"

(*woops, so it is!)

early go betweens single.

Peter Panic - Blur
Mr Briggs - Blur
Nord See - Blood Everywhere
Steven, You Don't Eat Meat - Sandie Shaw
Lloyd, I'm Ready To Be Heartbroken - Camera Obscura

andy warhol - bowie
sean flynn - clash

Dan Abnormal - Blur

...was a public figure given to whom the name actually referred.

Colin Zeal (Blur)
Ernold Same (Blur)
Arnold Lane (Pink Floyd)

Colin Zeal (Blur)
Ernold Same (Blur)
Arnold Lane (Pink Floyd)

.

Jesse James - The Pogues (among others)
Peggy Sue - Buddy Holly
Buddy Holly - Weezer
Alice Childress / Annie Waits / Eddie Walker / Fred Jones pt.2 - Ben Folds

Buck Rogers - Feeder

Malcolm X - Dennis Brown
Sharing a Gibson with Martin Luther King- Lambchop
The Ballad of Michael Valentine - The Killers
The Ballad of Dorothy Parker- Prince
The Ballad of Ira Hayes- Johnny Cash
The Ballad of Bjorn Borg - Pernice Brothers
John Walker's Blues - Steve Earle

Johnny Barleycorn - Frank Black
Rodney King - The Boo Radleys
Charles Bukowski Is Dead - The Bood Radleys
Jackie Wilson Said (I'm In Heaven When You Smile) - Van Morrison

A treasure trove, with a heavy emphasis on the early albums:

F*ckin' 'Ell It's Fred Titmus
I Hate Nerys Hughes (From The Heart)
The Len Ganley Stance
I Love You Because (You Look Like Jim Reeves)
Albert Hammond Bootleg
The Continuous Saga Of The Cremation Of Hattie Jacques
D'Ye Ken Ted Moult?
Rod Hull Is Alive - Why?
Dickie Davies Eyes
The Bastard Son Of Dean Friedman
Outbreak Of Vitas Gerulaitis
A Lilac Harry Quinn
Eno Collaboration
Hair Like Brian May Blues
Gubba Look-a-Likes
Bob Wilson - Anchorman
Visitor For Mr. Edmonds
David Wainwright's Feet

and

Achtung Bono (album)

Everett Ruess by Dave Alvin from the Ashgrove album.
He went off into the Utah desert and never came back.
Henry Darger by Natalie Merchant from the Motherland album.
The worst song on that album.

Plus a few from The Byrds:
Old John Robertson from The Notorious Byrd Brothers
John Riley from 5D
Jack Tarr the Sailor from The Ballad of Easy Rider
and I'll take a punt on
Pretty Boy Floyd from Sweetheart of the Rodeo

Wayne Rooney - Johnny Flynn
Hello,I'm Johnny Cash - Alabama 3
Sharing a Gibson with Martin Luther King - Lambchop
Talking New Bob Dylan - Loudon Wainwright

Sam Stone - John Prine
Paul McCartney - Scissor Sisters
Buddy Holly - Weezer
Bo Diddley - Buddy Holly

Does James Taylor's Machine Gun Kelly count?

A couple that do.
Tina Toledo's Street Walkin' Blues by Ryan Adams (sorry if that's already up there)
The Ballad of Lucy Jordan by Marianne Faithfull.

Seymour Stein - Belle and Sebastian

Andrew Ridgley - Black Box Recorder
The Ballad of Ritchie Lee - Spiritualised
Bela Lugosi's Dead - Bauhaus
Bill McCai - The Coral
Franz Schubert - Kraftwerk
Gary Gilmore's Eyes - The Adverts
Henry Lee - Nick Cave
Hey Jack Kerouac - 10,000 Maniacs
I'm Jim Morrison, I'm Dead - Mogwai
Ingrid Bergman - Billy Bragg
Jesse James - The Pogues
John Cope - Talk Talk
John Finn's Wife - Nick Cave
Johnny Cash - Sons & Daughters
Johnny Ryall - Beastie Boys
Julian H Cope - Julian Cope
Kevin Rowland's 13th Time - Dexy's Midnight Runners
Kitty Jay - Seth Lakeman
Let's Save Tony Orlando's House - Yo La Tengo
Levi Stubbs' Tears - Billy Bragg
Liza Radley - The Jam
Nelson Mandela - The Specials
The Night That Minnie Timperley Died - Pulp
Oliver James - Fleet Foxes
Pablo Picasso - Jonathan Ricmhond and The Modern Lovers
Peggy Suicide Is Missing - Julian Cope
Stagger Lee - Nick Cave
Tom Baker - The Human League
Tom Courtenay - Yo La Tengo

Singer-songwriter responsible for Barry McGuire's Eve of Destruction and Johnny Rivers' Secret Agent Man, was immortalized by Jimmy Webb (twice) and covered by Jennifer Warnes, The Association and Unicorn. Not quite first and last name but it counts, yes, Pete?

Maria Bartoromo by Joey Ramone

andrew ridgly : black box recorder passonia
bob lind (the only way is down) :pulp we love life
arther c clarke's mysterious world :the divine comedy victory for the comic muse
lord lucan is missing: black box recorder the worst of black box recorder
jack the ripper : the horrors strange house
the love of richard nixon manics lifeblood

i want to stay and play, but i'm about to be late for work

Irene Wilde - Ian Hunter, probably based on a real character, but with the name made up to rhyme with "Such beauty for a child"
Jenny Artichoke - Kaleidoscope, presumably fictitious
Judy Teen - Cockney Rebel
Marcus Garvey - by various reggae artists, I'd imagine
Christopher Columbus - Burning Spear
Billy Porter - Mick Ronson

And if we're allowed the name plus;
William Chalker's Time Machine - Lemon Tree

I said I was scraping the barrel, but I suspect it has a very thick bottom.

Good challenge, Peter: I like ones where you can't just google for answers.

Boom Boom Mancini - Warren Zevon

The Day I Saw Bo Diddley In Washington Square by Willie Nile and Sergio Leone by Jackson Browne

Lou Reed by the Little Willies. All about, perhaps mistakenly, seeing the song title bearer indulging in the old southern sport of cow tipping, aka pushing a cow over, I am assuming.
Strangely hard to imagine.

Both on the Train A Comin' album:
Tom Ames' prayer
Ben McCulloch
and no-one has mentioned

Flatt & Scruggs - The ballad of Jed Clampett (otherwise known as the theme to the Beverley Hillbillies).