James Corden has described the BBC as a "fundamental cornerstone of everything Britain stands for" as he voiced fears for the future of the publicly-funded broadcaster.
The Late, Late Show presenter spoke out as the Government prepares to announce its long-awaited White Paper on the BBC's future, which is expected to include a radical overhaul of the way the corporation is governed.
James, who achieved stardom on the BBC sitcom Gavin and Stacey, said he feared life without the organisation and he failed to understand people who were not "proud" of its service.
He told the Press Association: "How can you not be concerned about it? The BBC is so much bigger and greater than me standing here saying something as irrelevant as: 'I wouldn't have a career without it'.
"It is a fundamental cornerstone of everything Britain stands for. It is freedom of speech at its greatest.
"I consider it to be part of the foundation of all that is good in Britain. I fear for what life's like without it. I can't even begin to imagine it."
James, 37, is the latest star to defend the BBC after a host of top names spoke out at the Bafta television awards, including Wolf Hall actor Mark Rylance and its director Peter Kosminsky.
Speaking at the Rebels With A Cause charity gala in Los Angeles, James highlighted The Great British Bake Off, Strictly Come Dancing, Peter Kay's Car Share and Sir David Attenborough's documentaries as examples of the BBC's "incredible" programmes.
He said: "When you look at the output... for how many pence a day is it? It's something crazy right? You've got radio and the iPlayer and these incredible channels and BBC News, which is a news service bound by nothing, only actually telling you what's happening in the world.
"If it goes, if we lose it, I swear to God we're going to wake up one day and go; 'Oh, we didn't realise'.
"It is a brilliant and wonderful service that we should have nothing but pride in. I don't understand anyone that doesn't agree with that."
James, who moved to the US last year to begin hosting the Late, Late Show, had previously paid tribute to BBC Three before it became an online-only service after the channel was the first to broadcast Gavin and Stacey in 2007.