Tiger Woods’ dark side has been exposed in a bombshell new biography.

After RadarOnline.com exclusively revealed that his ex-wife Elin Nordegren had given birth to a child with her new boyfriend, the New York Post reported on the golfer’s revelations in the book.

Curt Sampson’s book Roaring Back: The Fall and Rise of Tiger Woods quotes sportswriter John Garrity, who first met Woods as a teenager, calling the star a “pathological narcissist.”

Garrity claims that by 2007, the once-likable Woods, now 48, had changed.

“A pathological narcissist. All of his human relationships are transactional. If you can’t help him achieve his goals, he doesn’t need you. He’ll walk right past you and see right through you,” Garrity tells the author in the book.

Sampson also calls Woods a miser.

According to the book, the golfer was notorious for tipping and underpaying one of his coaches.

As an amateur, Woods and his father, who died in 2006, reportedly stayed at the homes of golf club members rather than pay for their own accommodations, according to the book.

Dr. Al Oppenheim, who hosted Woods and his father, Earl, on two occasions, told Sampson, “They assumed we would buy them breakfast, lunch, and dinner…and we did, but they were not grateful. They never said thank you.”

Roaring Back also claims that Hank Haney, who coached Woods from 2004 to 2010, was paid just $50,000 a year.

According to Woods’ biography, Haney would have to use his salary to cover his living expenses while traveling with the millionaire golfer.

Sampson writes that Woods insists he never carries cash and notes, “Narcissists have no problem spending other people’s money because we already owe them money, and they have a hard time saying ‘thank you’ for the same reason.”

Woods reportedly considered becoming a Navy SEAL after losing the 2004 US Open.

The self-assured star even trained with the special operations unit at the age of 31, although the SEALS are not allowed to be over 28.

Woods reportedly told his golf club porter that the SEALS would make a “special exception” for him, which was documented in another book, Out of the Rough.

Sampson credits Woods’ father with making him feel invincible.

At Woods’ first press conference as a professional golfer in 1996, Earl said his son “will do more to change the course of humanity than anyone in the history of mankind” and that he was “chosen by God himself to raise this young man.”

“The father is great, the son is just great,” Sampson wrote.

A source confirmed to RadarOnline.com that Woods is heartbroken. “She was the love of his life and he knew there was no way he could get her back,” the insider said.