Shawn Michaels, HHH, Kane, Chris Jericho, Kurt Angle, Eddie Guerrero, Rob Van Dam, Booker T, Jeff Hardy, John "Bradshaw" Layfield and Christian. 

Those are the only wrestlers in WWE history to become Grand Slam Champions.

A Grand Slam Champion in the WWE is someone who has won a World title (WWE or WHC) an Intercontinental title, a tertiary title (European or Hardcore) and a Tag Team title (World TT or WWE TT).

By definition they are also Triple Crown Champions. 

Matt Hardy & The Big Show

Since neither the US nor the ECW titles count for the Grand Slam, Matt Hardy and the Big Show aren't considered Grand Slam Champions.

As of 2011 only six persons are elegible to become Grand Slam Champions: Goldust, William Regal, The Undertaker, The Big Show, Mark Henry and R-Truth.

Goldust and Regal need a World Championship.

Big Show and Undertaker need an Intercontinental title.

Mark Henry and R-Truth have it way harder as they need an Intercontinental, a Tag Team and a World Championship if they want to become Grand Slam Champions.

Since: May 1, 2011

The latest Grand Slam Champion.

He won the Tag Team, IC, European and Hardcore titles between 2000 and 2002. Almost 10 years later, he won his first World Championship to become the latest Grand Slam Champion.

He is so low on the list because he basically won the title for unforeseen circumstances (Edge's retirement) and lost it just two days after winning it.

Since: Dec. 4, 2008

Almost 10 years after his first WWE title, he became World Champion. Thanks to that title he also became Triple Crown and Grand Slam Champion.

While the journey was great and he accomplished all of it on his own, his antics stop him from being higher.

Since: July 23, 2006

Second person to become a Grand Slam in just three months. RVD won the WWE title in June and Booker T won the WHC in July.

Both of them became Grand Slam Champions after their World title wins.

Booker T only has the necessary titles to be Grand Slam Champion (World, IC, Tertiary and TT title).

He had some degree of success in the WWE, but he was far better in WCW.

Since: June 11, 2006

One of two people to win the Grand Slam in 2006, he last won the WWE title after cashing in his MITB contract against Cena at One Night Stand.

Much like Booker T, he enjoyed success in the WWE, but was far more successful before joining, in his case, in ECW.

Since: May 20, 2001

Second Grand Slam Champion of 2001, he won the Intercontinental title to claim his spot as a Triple Crown Champion and the third ever Grand Slam Champion.

His WWE title reign was almost nonexistent, but he redeemed himself in 2010 with his WHC run.

Since: March 9, 2009

After winning the Tag Team titles (with Faarooq) in 1999, the Hardcore title in 2001, the European title in 2002 and the WWE Championship in 2004, he won the Intercontinental title in 2009, thus becoming a Grand Slam Champion.

Also a long journey (10 years), but he was able to reinvent himself and held the record for longest World title reign in the last 15 years until Cena broke it in 2006.

Since: Feb. 15, 2004

He barely made it as he only has the exact requirements to be a Grand Slam Champion: A World title (WWE) a Tag Team title (with Chavo) a Secondary title (IC) and a tertiary title (European).

He also won the US title, but that one doesn't count to become a Grand Slam Champion.

A great entertainer, he had a lot of success in every promotion he worked for, including ECW, WCW and WWE.

Since: Oct. 20, 2002

After winning the WWE, Intercontinental and European titles in 2000, he won the Tag Team titles in 2002 (with Chris Benoit) to claim his spot as both a Triple Crown and Grand Slam Champion.

The only Olympic Gold medalist in Professional Wrestling earns a spot in the top five because of his speed, winning all four eligible titles plus a substitute belt in just three years.

Since: April 29, 2001

The first of three Grand Slam Champions crowned in 2001, he last won the Tag Team titles (with Stone Cold Steve Austin) to become the second Grand Slam Champion.

At the same time he became a Triple Crown champion.

One of the best ever, he isn't higher because of the accomplishments of the top two guys.

Since: Sept. 20, 1997

The first Grand Slam Champion.

After winning the IC title in 1992, the Tag Team titles in 1994 and a World title in 1996, Shawn Michaels went on to win the European title the next year making him the first WWE Grand Slam Champion.

He's also the fourth triple crown champion after Pedro Morales, Bret Hart and Diesel.

Only the fact that he never won the Hardcore title keeps him from the top spot.

Since: Dec. 9, 2001

Third of three Grand Slam winners in 2001. 

He won all titles in just three years, having won the IC title in 1999, he won the European title in 2000, and the Hardcore, World Tag Team and WWE titles in 2001. 

It also made him a Triple Crown Champion.

He would also win the WWE Tag Team and World Heavyweight titles, making him the only person to have hold all belts, regular and substitute to be a Grand Slam Champion.