The S&P 500 is down about 40% over the last 12 months. There have been nearly 190,000 layoffs at America's 500 largest companies in just the last six weeks. And the U.S. government is spending a trillion dollars to keep the economy afloat.

This year's edition of the Forbes Fictional 15, our annual listing of fiction's richest, features significant turnover and turmoil.

More than half of last year's members fell off the list, and those who remain are poorer on average; 12 months ago, you needed at least $1.3 billion to make the cut. This year, you only need $800 million.

Economic woes thrust a new member of the Fictional 15 to the top spot: Uncle Sam, the 232-year-old former frontiersman and U.S. Army recruitment officer.

This American icon is enjoying a second act on Wall Street, thanks to his contrarian strategy of investing exclusively in companies on the brink of bankruptcy. His infinite net worth can be attributed to his crafty purchase of the U.S. Mint in 1792; this guy can print his own cash.

Last year's richest fictional character, Scrooge McDuck, fell to second place, with a net worth of $29.1 billion. But don't feel bad for the quacking Croesus; the record-high price of gold increased his fortune significantly.

McDuck's bottom line was also buoyed by his penny-pinching ways and lack of charitable giving.

Third place Richie Rich wasn't as lucky. "The richest kid in the world" saw his net worth tumble from $16.1 billion to $12.3 billion thanks to ill-timed investments in Web 2.0 start-ups.

But despite these setbacks, Rich continues to make splashy charitable donations, including airdropping cans of foie gras onto starving Kurdish villages and leaving $1 million tips for waitresses.

Eight former billionaires dropped off the list, including Willy Wonka , whose candy company was hit hard by the rising cost of cocoa beans. Dark wizard Lucius Malfoy lost big investing in cauldron derivative swaps. And Princess Peach, heir to the Mushroom Kingdom, fled abroad after a revolution toppled her regime.

Peach is reportedly in close consultation with advisers, hoarding fire flowers and invincibility stars, and plotting return to power.

Shifting fortunes caused some members to return to the list. Corporate raider Gordon Gekko (No. 4, net worth $8.5 billion) is widely credited on Wall Street for creating collateralized debt obligations. He fell off the list in 2005 after being convicted of insider trading and securities fraud. Now out of prison, Gekko shorted the S&P 500 and bank stocks near their peak. Conspicuously seen celebrating at Manhattan restaurant the night Lehman Brothers collapsed, he's quoted as saying, "Greed is good . . . for me, not them!"

Who did we miss? Tell us your choices for the richest fictional characters!

Not all of our new members are from planet Earth. Jabba The Hutt (No. 5, $8.4 billion) oversees a massive crime syndicate in the Outer Rim Territories, controlling gunrunning, extortion and the Kessel spice trade. This morbidly obese billionaire employs an elite staff of bounty hunters, assassins and never-do-wells; associates say he "has no use for smugglers who drop their shipments at the first sign of an Imperial cruiser."

This year, the Fictional 15 also features a listing of the world's most expensive fictional homes. These properties span the real estate gamut from Tony Stark's sweet bachelor-pad in Iron Man ($50.8 million) to Tara ($17.2 million), the antebellum plantation from Gone with the Wind. The source material was equally varied, ranging from videogames (Croft Manor from Tomb Raider, $46.1 million) to literature (Jay Gatsby's West Egg mansion from The Great Gatsby, $42.5 million).

To qualify for the Fictional 15, we require that candidates be an authored fictional creation, a rule which excludes mythological and folkloric characters. They must star in a specific narrative work or series of works.

And they must be known, both within their fictional universe and by their audience, for being rich. Net worth estimates are based on an analysis of the fictional character's source material, and valued against known real-world commodity and share price movements. In the case of privately held fictional concerns, we sought to identify comparable fictional public companies.

All prices are as of market close, Dec. 17, 2008.

We reserve the right to bend or break any of our own rules. And, yes, we know Uncle Sam is folkloric.

• In Pictures: The Most Expensive Fictional Homes