Stephen Fry is to take over from Central Library security staff to do announcements to visitors at closing time this week.
The Blackadder star's voice will be boomed out at 7.45pm on Tuesday, Wednesday and Thursday as staff prepare to close at 8pm.
Stephen will ask people to gather their belongings and check out their books.
"Ding dong! Hello, sorry to disturb you," his message will begin.
"This is Stephen Fry here just letting you know that the time is now, well, it's a quarter to eight in the evening.
"Now's the time to pop your pencils and pens in their cases, and fold your folders, and pop away your books and gather your personal belongings generally and make your way, if you can, to the exit."
He'll also speak about his love for lirbaries.
"Thank you most of all for using the library," he will add.
"Aren’t libraries magical, sacred places?
"And the more you use them and the more you remind other people of their existence and recommend that they use them too, the better it will be for the health of the nation.”
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Other famous voices have previously included Brian Blessed OBE, Happy Mondays' singer and The X Factor star Rowetta and actor Julie Hesmondhalgh.
Executive member for skills, culture and leisure, Coun Luthfur Rahman, said: “We wholeheartedly share Stephen’s passionate belief in the importance of libraries, which are vital spaces offering access to books, computers, information, learning and social activities - for the whole community, for free.
“We’re proud that Central Library now welcomes two million visitors every year and there’s no doubt that Stephen has added a little extra magic for our library members through this wonderful message.”
Manchester's citywide network of libraries have issued out more than 1.3 million books and audio materials in the last year alone.
