Veteran broadcaster Sir Terry Wogan has pulled out of presenting charity fundraiser Children in Need due to health reasons, the BBC said.
The 77-year-old confirmed he would miss the "wonderful, inspiring evening" for the first time after hosting the annual event every year since it began in 1980.
The Radio 2 star is having a procedure on his back and has been told by doctors he cannot present a six-and-a-half-hour show, a BBC spokesman said.
Sir Terry said: "The British public, as always, will dig deep in their pockets and purses to help the country's disadvantaged children, knowing that every penny will go to those who need it most.
"I'm going to miss our wonderful, inspiring evening together, but I'll be with you, watching, cheering and donating to a magnificent cause."
A BBC spokesman said: "We are so sorry that Terry won't be with us tomorrow night as we know how passionate he is about Children in Need.
"But we wish him a very speedy recovery and know he'll be watching from home and enjoying the show."
A replacement host will be announced in due course, the BBC said.
Tess Daly, Rochelle Humes, Nick Grimshaw and Fearne Cotton, who had been set to join Sir Terry on the show, will continue with their presenting duties.
Sir Terry said he had been "proud" to host Children in Need - in its 36th year - since the show launched but he would not be there "to cheer you on with word and gesture to another record-breaking year".
He added: "The show will go on, bigger and better than ever, in the hands of my friends, Grimmy, Fearne, Rochelle and Tess."
The loss of Sir Terry to the show comes after Storm Abigail forced BBC Radio 1 DJ Scott Mills to change the location of his abseil for Children in Need because of safety concerns.
Mills was due to abseil down the 400ft Blackpool Tower to raise money for the charity, but a last-minute change means he will now be tackling the ArcelorMittal Orbit in London's Olympic Park.
Sir Terry has faced criticism in previous years after it emerged he had been paid £1,300 an hour for hosting the annual charity appeal on BBC1, although he insisted he did not know about the fee, and had waived it.
Since its launch in 1980, Pudsey the Bear and co have raised nearly £800 million for children's charities in the UK.
One Direction and Dame Helen Mirren are among the stars hoping to make this year's Children in Need the biggest yet.
Former Doctor Who star David Tennant, Sherlock actor Martin Freeman and singer Ellie Goulding are also expected to present some of the inspiring projects funded by the appeal.
Goulding is set to perform her new single and there will be an exclusive Star Wars sketch with C3PO and R2-D2 alongside Star Wars actor Warwick Davis.
Pop star Jess Glynne will sing Take Me Home, the official BBC Children in Need single.
Other highlights include a one-off special in which comedian Harry Hill will take viewers on a whirlwind tour of the history of TV in his own inimitable style.
There will also be a Call The Midwife Strictly special and performances from music stars Rod Stewart, Selena Gomez, Years and Years as well as Anastacia.
BBC Children in Need supports 2,500 projects. In the last year alone, the charity has helped nearly half a million disadvantaged children.
:: Children in Need airs on Friday at 7.30pm on BBC One.