A few months ago, news emerged that Michael Jackson's estate has risen to more than $1bn since his death, overtaking Elvis Presley's. This is ironic considering that the singer was calculated to be nearly $494m in debt when he died in June of 2009.
But at least Jackson was able to enjoy wealth and comfort during his lifetime. Others weren't so lucky - as demonstrated earlier this month when the wills of various famous figures, including the likes of Charles Darwin and Karl Marx, were published for the first time.
For instance, Irish-born playwright Oscar Wilde died destitute in Paris in the year 1900, aged just 46, leaving behind him just £250. Like Jackson however, Wilde's influence on culture can still be felt in popular culture, and his memorabilia remains a great investment.
Here, we pick out some of our favourites from the published wills - among six million put online, all dating from 1861 to 1941 - and compare their values to recent collectibles performances on the auction block.
Oscar Wilde (1854-1900)
Controversy dogged Wilde throughout his life, and his 1892 play Salomé was no exception when Lord Chamberlain's licensor banned the play in London for its illegal depiction of biblical characters.
Nevertheless, the play eventually had its debut performance at Paris's Theatre de l'Oeuvre, on February 11, 1896 - the same city in which Wilde would die four years later.
Earlier this year, A previously unknown First Edition of Salomé emerged on the markets having been stored in an attic for years. It was all the more remarkable for containing a handwritten inscription by Wilde himself to the French Symbolist painter, Gustave Moreau.
Sold in its original purple wrapper printed in silver, the book auctioned with an estimate of £20,000-30,000, eventually selling for £34,000.
In comparison, at the time of his death in 1900, Wilde left £250 which would today be worth £9,000.
Lewis Carroll (1832-1898)
Alice's Adventures in Wonderland and its sequel, Through the Looking-Glass, remain Carroll's most famous works. This ongoing influence was reflected at auction in December, 2009, in a sale by US auctioneers Profiles in History.
The sale grossed $551,454 in total. Among its major highlights was a First Edition, dedication copy of Through the Looking-Glass, and What Alice Found There. This very special copy of the book was dedicated Alice Pleasance Liddell, on whom the fictional Alice based.
As well as featuring her signature, at the back of the book is hidden an acrostic poem which spells out Alice's name. Only three such books were ever presented in red binding, and only one bears Liddell's signature - it eventually sold for $115,000.
In today's money, this was roughly a quarter of what Carroll - real name Charles Lutwidge Dodgson - was worth upon his death in 1898. He left £4,596 - today worth £450,000.
Sir Arthur Conan Doyle (1859-1930)
Today, Sir Arthur Conan Doyle is best-remembered for his Sherlock Holmes novels. Yet, during his lifetime, the author wished to instead be remembered for his psychic work and published 60 works on spiritualism.
Nevertheless, Conan Doyle's innovative and influential crime fiction novels continue to win the hearts of new generations of readers and, this year alone, Sherlock Holmes has starred in his own blockbuster Hollywood film (starring Robert Downey Jr) and a successful BBC TV series.
The author was also lucky enough to enjoy the fruits of his success during his lifetime. Conan Doyle died in 1930, leaving behind £63,491 in his will - which would today be £3 million.
Charles Dickens (1812-1870)
Like Conan Doyle, Dickens also enjoyed significant fame and wealth during his lifetime. And his vividly descriptive works still regularly capture the imaginations of film and television executives to this day.
Dickens remains the most popular and widely-read author of the Victorian era - and this naturally translates to his performance on the auction block. Sales have included some rather strange items, like the collar worn by his dog which auctioned for $11,500 back in March.
Currently available on the market is a lock of the Great Expectations author's hair, with a copy of an authenticating note written by Dickens' sister-in-law, Georgina Hogarth.
Strands of Dickens' hair are today valued at £1,750, and it's value is sure to appreciate in the future. In comparison, when Dickens died in 1870, he left behind £80,000 - which today equates to £7.1 million.
Charles Darwin (1809-1882)
By the time of this death, Darwin (pictured top right) will already regarded as among the world's most eminent minds. He wrote two books which changed all our lives - one of which, The Origin of the Species, has positively changed the lives of collectors over the years too...
In January of this year, for instance, Christie's sold a first edition copy of Darwin's On the Origin of the Species by Means of Natural Selection. Bizarrely, the copy had been kept carefully in the toilet of an Oxford home for decades.
Despite its unusual provenance, the book didn't disappoint when it sold on the 150th anniversary of its original publication estimated at £40,000-60,000 (up to $100,000), natural selection by enthusiastic bidders saw it finally get taken home for £103,250.
And Darwin himself was no stranger to large sums of money during his own lifetime. When he died in 1882, he left behind an estate worth £146,911 - which would today be worth £13 million.
However, whether any of Darwin's beard hairs are likely to appear for sale remains to be seen.
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