The Fifth King: Booker T
After Macho King was forced to retire, the WWE sort of swept the crown and scepter under the rug. The title of King was forgotten for many years as the WWE focused on more 'relatable' gimmicks, such as TL Hopper the wrestling plumber, or Duke Droese the wrestling garbage man.
The crown was ceremoniously given to the King of the Ring tournament winner each year, but they didn't make a practice of wearing it afterward as part of their gimmick.
However, in the Ruthless Aggression era, the crown was brought back when Booker T won the 2006 King of the Ring tournament. Now calling himself King Booker, he and his queen Sharmel would demand respect from all the babyfaces in WWE.
Booker played the gimmick to perfection and even referenced the same in his Hall of Fame speech as one of the highlights of his career.
Vince McMahon was a huge fan of King Booker, and he would even win the WWE World Title during this period. He was forced to defend his belt against the champions of Raw and ECW, and came out the winner.
Eventually, Booker T would leave the company, leaving the WWE once more without a king.