Celebrities took to their Twitter accounts to pay tribute to radio legend Casey Kasem – who passed away at the age of 82. Kasem was best known as the long running host of American Top 40 and also provided the voice of Shaggy in the Scooby-Doo cartoons. His name was also in the headlines recently as his three children battled with his second wife Jean over his care. LOS ANGELES In Los Angeles, game 5 of the Stanley Cup Finals was a hot ticket for celebs. Spotted at the Staples Center were the likes of Channing Tatum, Chris Pine, Chloe Grace Moretz, Taylor Kitsch, Joe Jonas and Joshua Jackson. Joshua Jackson: Elsewhere in LA, Holly Robinson Peete and Kat Graham of “The Vampire Diaries” were among the honorees at a fundraiser for Children Mending Hearts. :19 Kat Graham: I really don’t…globally :34 LONDON There was even more giving back in London as Samuel L Jackson hosted a charity ball for the men’s cancer foundation One For the Boys. The event was part of the menswear fashion week London Collections. Also in attendance: Chris Evans, Jeremy Piven and Colin Firth.