PEOPLE Magazine 40th Anniversary

Look Who's Turning 40

From Leonardo DiCaprio and Victoria Beckham to Hello Kitty and Happy Days, see who's celebrating the milestone with PEOPLE

RYAN SEACREST

These days, the American Idol host is a full-fledged media mogul and as he nears the big 4-0 on Dec. 24, he admits that he may have to start acting a bit more adult in his personal life. So, Seacrest adopted a dog, which he told PEOPLE, "is me saying to myself, 'You should have a little responsibility' ... I'm turning 40 and it's a turning-point number. You go, 'Wait, you've got to grow up a little bit.'"