Siôn Dafydd Rhys, in Latin Joannes David Rhaesus, also called John David Rhys, or John Davies (1534 –  1609 ), was a Welsh physician and grammarian.
David Rhys Williams (1890 – March 28, 1970) was an American Congregational and Unitarian minister who wrote a Marlovian book called "Shakespeare Thy Name Is Marlowe".
Sian Williams (born 23 October 1990) is a Welsh rugby union player who plays in the back row for Worcester/Newport Gwent Dragons and the Wales women's national rugby union team.
 She won her first international cap against Scotland in the 2011 Women's Six Nations Championship.
 She is the younger sister of Wales Rugby League international Rhys Williams who is Wales' all-time top try scorer in that code.
Ulrika Spacek are an English alternative rock band, formed in 2014 and currently composed of singer-guitarist Rhys Edwards, guitarist Rhys Williams, guitarist-keyboardist Joseph Stone, bassist Ben White and drummer Callum Brown.
Sir Rhys Rhys-Williams, 1st Baronet DSO QC DL (20 October 1865 – 29 January 1955), born Rhys Williams, was a British Liberal Party politician from Wales.
 He later left the Liberal Party for the Conservatives.
The Williams, later Rhys-Williams Baronetcy, of Miskin in the Parish of Llantrisant in the County of Glamorgan, is a title in the Baronetage of the United Kingdom.
 It was created in 1918 for Rhys Williams, Member of Parliament for Banbury from 1918 to 1922.
 He assumed in 1938 by deed poll the additional surname of Rhys.
 The second Baronet was a Conservative politician.
 As of 2014 the title is held by the latter's son, the third Baronet, who succeeded in 1988.
Christopher Marlowe, also known as Kit Marlowe (baptised 26 February 156430 May 1593), was an English playwright, poet and translator of the Elizabethan era.
 Marlowe was the foremost Elizabethan tragedian of his day.
 He greatly influenced William Shakespeare, who was born in the same year as Marlowe and who rose to become the pre-eminent Elizabethan playwright after Marlowe's mysterious early death.
 Marlowe's plays are known for the use of blank verse and their overreaching protagonists.
Rhys Williams (born 14 July 1988) is an Australian professional footballer who plays for Australian club Melbourne Victory FC and the Australia national team.
 A very versatile player, Williams is adept at playing as a centre back, defensive midfielder and right back but has played in virtually every out-field position at some point for Middlesbrough including more attacking roles.
 In August 2012, Williams was made club captain of Middlesbrough.
Verity of Sydney Town (1950) is a children's book by Australian author Ruth C. Williams; it was illustrated by her husband Rhys Williams.
 It was won the in 1951.
The Marlovian theory of Shakespeare authorship holds that the Elizabethan poet and playwright Christopher Marlowe was the main author of the poems and plays attributed to William Shakespeare.
 Rather, the theory says Marlowe did not die in Deptford on 30 May 1593, as the historical records state, but that his death was faked.

Question: David Rhys Williams wrote about what theory that Marlowe was the author of Shakespeare plays? 
Answer: Marlovian theory