Between 12 and 27 percent of pet owners provide provisions for their pets in their wills, according to the Washington University School of Law. In fact, pet trusts have become so popular that 39 U.S. states now have statutes outlining them. In most cases, these trusts are relatively small — typically in the $30,000 range — but some pampered pets inherit millions of dollars, in addition to property, jewelry and a lifetime of prearranged pampering.

Take a look at some of the world's wealthiest animal heirs.

Trouble: Hotel heiress Leona Helmsley, who died in 2007, made her Maltese her biggest heir, leaving a $12 million trust fund for the pooch in a will that disinherited two of her grandchildren. A judge later knocked the pup's inheritance down to $2 million, and Trouble took the money and retired, flying by private jet to the Helmsley Sandcastle hotel in Sarasota, Fla. The hotel's general manager cared for the dog and spent hundreds of thousands on her care annually, including $1,200 on food, $8,000 on grooming and $100,000 for full-time security. (Trouble had received death threats.) The little Maltese passed away in December at the age of 12, and her remains were supposed to rest beside Leona's in the family mausoleum, but the cemetery refused. Instead, Trouble was cremated and her remaining money went to the Helmsley Chairtable Trust.

Nicholas: When British singer Dusty Springfield died in 1999, she instructed that her money be used to care for her 13-year-old ragdoll cat. The will stipulated that Nicholas be fed imported American baby food and live in a 7-foot-high indoor treehouse with amenities that included catnip, scratching posts and a bed lined with one of Springfield’s nightgowns. Nicholas was also to be played Springfield’s recordings each night before bedtime. The singer even arranged for her cat to be “married” to a 5-year-old English blue breed that belonged to her friend, Lee Everett-Alkin, whom she named as and Nicholas’ guardian.

Flossie: In 2002, Drew Barrymore surprised her Labrador mix, Flossie, with a new doghouse — she placed her Beverly Hills home in trust with the pooch. What inspired such an extravagant gift? In 2001, Flossie barked and “literally banged on the bedroom door” to awaken Barrymore and Tom Green, her husband at the time, to alert them of a house fire. Flossie saved their lives and now stands to inherit a $1.3 million house, making her a milionaire mutt.

Bubbles: Michael Jackson left his chimp $1 million to ensure he would have a “secure long-term future,” but so far Bubbles hasn’t seen a penny of his inheritance. The chimp now lives in an animal sanctuary in Florida, and animal trainer Bob Dunne says he’s not sure if Bubbles will ever receive his share of Jackson’s money.

Minter, Juice, and Callum: Before British fashion designer Alexander McQueen hanged himself in 2010, he left a note that read, “Look after my dogs, sorry, I love you, Lee” — as well as $81,000 for the three English bull terriers’ care. The money was put into a trust for the canines and will pay for their care for the rest of their lives. Most of McQueen’s remaining fortune was donated to animal charities.

Tinker: In a true rags-to-riches tale, Tinker the stray black cat began frequenting the London home of Margaret Layne, a wealthy widow, and won the woman over, inheriting her $800,000 home when she passed away in 2003. But she didn't leave him just a house, she also created a $226,000 trust fund for Tinker and gave a hefty sum to her former neighbors so they could look after the cat and his new home. However, the inheritance came with strings attached — if Tinker returns to his straying ways, he relinquishes ownership of the house. But according to reports, Tinker has decided to settle down and has taken up with a single mother cat and her kitten.

Conchita, Lucia and April Marie: Heiress Gail Posner left $3 million to her three Chihuahuas, as well as diamond dog accessories and an $8 million mansion in Miami. The dogs’ live-in caretaker also inherited millions.

Gunther IV: When Carlotta Liebenstein, a German countess, died in 1991, she left her fortune to her dog Gunther III. The canine died a month later, but his wealth was passed on to his son, Gunther IV, whose estimated worth is $372 million, making him the richest pet in the world. Gunther is said to have a personal maid and a chauffer-driven limo, and there are even reports that he owns a home in Miami that once belonged to Madonna.

Blackie: When British antiques dealer Ben Rea died in 1988, he bequeathed his $12.5-million fortune to Blackie, the only surviving cat of the 15 cats he shared his mansion with. The recluse overlooked his family and split the majority of his wealth between three cat charities, with instructions to look after his beloved pet.

Red: Often referred to as the “million-dollar tabby,” Red was the beloved cat of Canada’s reclusive David Harper who died in 2005 with no heirs except his pet. Harper left his $1.3 million estate to the United Church of Canada, but in exchange for the money, he stipulated that the church would have to look after 3-year-old Red. The rich feline was the last in a long line of orange tabby cats named Red that Harper took in over the years.

Kalu: Once thought to be the second wealthiest pet in the world — worth roughly $65 million — Kalu the chimp seems to have lost his inheritance. Patricia O’Neill, the daughter of the Countess of Kenmore and ex-wife of Olympic swimmer Frank O’Neil, found Kalu tied to a tree in war-torn Zaire in 1985 and he quickly became her closest companion. She changed her will so that her estate in Cape Town would go to Kalu, and she set aside money so that he and her other rescued animals — 30 dogs and 11 cats — would be cared for after her death. However, in 2010, O’Neill learned that most of her money had been stolen, leaving her with just $100,000. “I don’t know how much will be left when I die,” she’s said. “I don’t want to spend much money because I am determined that my animals will be cared for."

Jasper: Diana Myburgh, a brewery heiress, rescued Jasper, a Labrador and Doberman mix, from an animal shelter and brought him home to live with her and her Whippet, Jason. She cared for the dogs until she died in 1995, but she left each of them a trust fund of $50,000 — in addition to her 1,236-acre estate that’s worth more than $1 million. When Jason passed away, Jasper inherited his money, and the dog moved in with Myburgh’s former son-in-law, Sir Benjamin Slade, who feeds him tripe, his favorite dish. Slade once considered having Jasper cloned, but this angered trustees who stand to inherit Jasper’s money when he dies.

Tobey Rimes: New York heiress Ella Wendel died in 1931 and willed $30 million to her French poodle, Tobey Rimes, who slept in his own brass bed beside Wendel. According to reports, that fortune has been passed down through the years to the descendants of the original dog — all named Tobey Rimes — and even grown over time. The current Tobey is said to be worth millions.

Oprah’s dogs: The retired talk show host — whose net worth is $2.7 billion, according to Forbes — plans to take good care of her dogs even after death. She’s reportedly set aside $30 million for her beloved pack of pups.

Betty White's pets: According to newspaper reports, White plans to leave a $5 million trust to her animals.

Trekkie pups: Star Trek creator Gene Roddenberry’s widow, Majel Barrett-Roddenberry, who was also an actress in the original series, set up a $4 million trust for her dogs. She even left $1 million to her domestic employee Reinelda Estupinian to take care of the canines. In the trust papers, Majel said that Estupinian "did an excellent job of caring for my animals, giving them comparable or better care than that which I gave them during my lifetime."

Also on MNN: Pitfalls of bequeathing money to pampered pets

Click for photo credits

Photo credits:

Leona Helmsley: ZUMA Press

Bubbles: Getty Images

Gail Posner: ZUMA Press

Patricia O'Neill: Wikimedia Commons

Oprah: Globe Photos