Nina Dobrev, Joe Jonas
Credit: George Pimentel/WireImage

Joe Jonas and Nina Dobrev teamed up to host We Day in Toronto, an all-day benefit for the charity Free The Children. "Wow!!! We Day rocks, So many amazing kids, such great energy!" Dobrev (in a Rachel Zoe tuxedo jacket) tweeted from the event. Click through to see Alexa Chung, George Clooney and more stars at last night's hottest events!