As a segment of America's population rallies around Democratic lawmakers who staged a sit-in to advocate for stronger gun control legislation, our neighbors across the pond are experiencing a defining moment of their own: Voting citizens of the United Kingdom (UK) are awaiting the results of a referendum that will decide whether the UK will remain with the European Union, or if they will (BR)exit and separate. The "Brexit" debate has evoked strong opinions on both sides, and UK-born celebrities are no exception.

Lily Allen has been a vocal advocate of remaining in the EU, particularly after vocally anti-Brexit British politician Jo Cox died on June 16 after she was shot and stabbed in the street by a man who reportedly said his name was "Death to traitors, freedom for Britain" in his subsequent court appearance. Allen's engaged both Brexit opponents and supporters on Twitter, and urged everyone who's able to action.

"Get out and vote tomorrow, it's so important," Allen tweeted yesterday (June 22). "I'm voting IN #VoteRemain  #BritsDontQuit."

Late Late Show's James Corden, J.K. Rowling and One Direction's Niall Horan were also among the UK-born celebrities to mobilize voters online, with some offering explanations for why they were in favor of keeping the UK in the EU but ultimately pushing for participation above all.

"Voting day!," tweeted 1D's Horan, who's gone on record as an avid voter in the past. "Very important that if you have a vote, use it !" 

Wise words, both here and abroad. Check out more stars' thoughts — including London-residing American comic Rob Delaney — on the Brexit referendum below.

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