There's an obit on the wires for actress Argentina Brunetti that's headlined, "It's a Wonderful Life's Last Surviving Adult Cast Member, Argentina Brunetti, Dies at 98 in Rome, Italy." Here's a link to it.
But of course, we all know that's not so. Charles Lane was certainly an adult when he made the film — he was older than Ms. Brunetti, in fact — and he's very much alive. Mr. Lane will be celebrating his 101st birthday next month.