Michelle McCool debuted as part of the Diva Search in 2004, and would become a villainous manager in 2006. Michelle resurfaced in June 2 with a "hot teacher" gimmick, serving as the evil centerpeice of the "Teacher's Pets," KC James and Idol Stevens. In her villainous role, Michelle engaged in feuds with Ashley Massaro and Jillian Hall.
After becoming WWE's first ever Divas Champion, Michelle's heel persona began to resurface in November of 2008, beginning when she defeated Maria Kanellis to remain champion. After Survivor Series, Michelle and Maria faced each other on the December 5 edition of SmackDown in a non-title rematch. Michelle portrayed the villainess and attempted to destroy Maria, but she ended up losing the match in the process. Michelle snarled evilly at Maria after the match, and she later attacked Maria backstage; claiming that she got what she deserved.
On the final SmackDown of 2008, Michelle lost the Divas Championship to Maryse in a match officiated by Maria, and later attacked to cement herself as a villainess, all the while claiming that Maria cost her the title. The following week, the evil Michelle snapped at Eve Torres during a backstage interview, and later attacked her after feigning an apology. Michelle's second run as a villainess led to her capturing the Women's Championship at The Bash in 2009; doing so by defeating Melina.
It was around this time that Michelle showed how truly sadistic and dangerous she could be, as she set out to cause as much damage to the rest of the roster as possible. She would leave opponents unable to walk because she refused to release her deadly heel hook hold. But the attack that seemed to give her the most pleasure was when she would smash her knee into people's heads against the ringside barricade and announcer table.
Michelle aligned with Alicia Fox in the early months of the year, but it was in the fall of 2009 that she formed her famous alliance with the evil Layla. Collectively known as "LayCool," the duo tormented and bullied Mickie James for several months, and even feuded with Beth Phoenix entering 2010. Michelle would add another reign as Women's Champion during that year and would become the first ever Unified DIvas Champion when she defeated Melina in a Lumberjill Match at Night of Champions. After losing a six-person tag match at WrestleMania 27, Michelle turned against Layla, leading to a Loser Leaves WWE match at Extreme Rules on May 1, 2011, which Michelle lost.