Christopher Marlowe is often suggested as Shakespeare's rival and as the real author of Shakespeare's plays. Others, such as Ben Jonson, might be put forward as the authors of Shakespeare's plays but not simultaneously as his rivals. One of Shakespeare's sonnets is offered as evidence that Marlowe and Shakespeare were rivals for the patronage of the man to whom many of the sonnets are addressed. Here is Sonnet 86:

Was it the proud full sail of his great verse,
Bound for the prize of all too precious you,
That did my ripe thoughts in my brain inhearse,
Making their tomb the womb wherein they grew?
Was it his spirit, by spirits taught to write,
Above a mortal pitch, that struck me dead?
No, neither he, nor his compeers by night
Giving him aid, my verse astonished.
He, nor that affable familiar ghost
Which nightly gulls him with intelligence,
As victors of my silence cannot boast;
I was not sick of any fear from thence:
But when your countenance fill'd up his line,
Then lacked I matter; that enfeebled mine.

Marlowe had a reputation for dealing in such things as sorcery and devil worship. The sonnet suggests that he was getting help in his creative writing from invisible spirits and from a "familiar ghost" (someone like Mephostopilis in Marlowe's Doctor Faustus). It has been suggested that Marlowe was not really killed in a tavern fight in 1593, as is generally supposed, but that he faked his death and fled the country because he was in imminent danger of being arrested for such outlawed practices as witchcraft, black magic, and sorcery and probably burned at the stake. If Marlowe was still alive and residing in some country like France, or even hiding out in England under an assumed name, so the theory goes, he could have been writing the plays attributed to Shakespeare and using Shakespeare as a "front." This theory, like many of the others about the "real authorship" of Shakespeare's plays, will probably go on forever; and no doubt there will be new books appearing every few years in which someone offers new evidence proving that Christopher Marlowe was the real author of Shakespeare's plays.

Marlowe was undoubtedly a highly gifted poet and playwright. He is one "likely suspect" who probably really could have written at Shakespeare's genius level. According to the eNotes biography of Marlowe:

The son of John and Catherine Arthur Marlowe, Christopher was born on February 6, 1564, and was thus almost an exact contemporary of Shakespeare, who was born on or near April 23 of the same year.

William Shakespeare had many rivals in the competition for audiences and patronage in Elizabethan England. Christopher Marlowe can be regarded as one of his major competitors. Another type of competition occurred on the literary rather than economic level in controversies about style. Ben Jonson and the 'school of Ben' are sometimes contrasted with the 'school of Will' as emphasizing classical style and reason against many of the extravagances and improbabilities seen in the works of Shakespeare.

On the question of authorship, although the authorship of a few minor plays is disputed, the overwhelming majority of Shakespeare's works are firmly attested as belonging to him. The theories proposing other authors, such as Bacon or the Earl of Essex, are not taken seriously by scholars or advanced students; they are more on the order of science fiction or fantasy than serious historical analysis.