The most random group of stars were on hand this evening (October 27) for the highly-anticipated premiere of This Is It in Los Angeles.

Unlikely date Katy Perry and American Idol runner-up Adam Lambert were among the first on the red carpet as they eagerly waited to watch the feature-length documentary detailing Michael Jackson’s planned comeback concerts.

Other celebrity attendees stepping out to watch the Gloved One do his thing included the likes of Jennifer Lopez, Ashley Tisdale, Monique Coleman, Paris Hilton, Paula Abdul, Jennifer Love Hewitt, Jamie Kennedy and JC Chasez.

Though admittedly a fan (aren’t we all?), Katy revealed that she was only there to promote Adam’s album. Both made sure to tell each and every news outlet that his debut album drops November 23.

Talk about a lack of decorum!

Meanwhile, Michael’s kids saw their late father’s concert rehearsal movie at a private screening this evening.

The two Prince Michaels and Paris were invited to the Sony Studios lot in Los Angeles, so they could see their dad in action one last time — on the same night international journalists got to see the film for the first time.

Their uncle Jackie is the only family member who has confirmed he has seen the film — he attended a screening last week, and called the movie “truly riveting”.

Sources close to the Jacksons say the kids have been sick with the flu for the past week, but they were well enough to attend the screening tonight.