Prince William has congratulated Sir David Attenborough on reaching a "remarkable milestone", as the broadcaster and environmentalist celebrated his 100th birthday.
Sir David's seven-decade career was marked with a night of memories, live music and special guests at a special concert at London's Royal Albert Hall on Friday.
"It is a rare privilege to celebrate a century of life," Prince William said, "but it is rarer still when that person has transformed the way we see the only home that we have - planet Earth."
Meanwhile, a cast of helpers from the natural world helped deliver a card written by King Charles from Balmoral Castle in Aberdeenshire to Sir David's hands at the concert in London.
Birthday messages from a string of A-listers including Leonardo DiCaprio and Dame Judi Dench were played on screen during the show.
Guests joining host Kirsty Young on stage included broadcaster Sir Michael Palin, a friend of Sir David's, while there were performances from musicians including Sigur Rós and Bastille's Dan Smith.
In a pre-recorded video, the King was seen writing his letter to Sir David, which said he and the Queen sent their "warmest congratulations on such a special occasion".
Over the decades, the King continued, Sir David had "revealed the beauty and wonders of nature to audiences around the world in new and marvellous ways".
"In so doing, you have shared my determination to highlight the urgent need to protect and preserve this precious planet of ours - and all life on Earth - for future generations.
"Thank you for all that you have done, and on behalf of the whole nation, I wish you a very happy 100th birthday."
The Queen's dog, Moley was seen scampering around the King's feet as he composed the letter, and recounted his seven-decade friendship with the broadcaster.
King Charles first met Sir David in 1958 as a nine-year-old, when he visited the set of BBC children's programme Zoo Quest - which gave Sir David his big break as a TV presenter.
The King noted their encounter came "almost a decade before the age of colour television, and of course our paths have crossed many times since".
Sending the letter on its way, viewers watched as it encountered a series of obstacles along the way, starting with a fallen tree in the road.
But a string of helpers from the animal kingdom, including eagles, a hedgehog, a red squirrel and a flock of geese, were seen delivering the letter down the British isles.
The letter eventually reached the hands of Sir David - who held it up to the audience at the Royal Albert Hall, prompting one of several standing ovations from the crowd over the course of the night.
In his speech, Prince William told Sir David: "Like millions across the world, my children have grown up with your incredible storytelling - a window into the wonders of nature that shaped their understanding of our planet, and their belief that it is something worth fighting for.
"And for me personally, your friendship has been profound. You have strengthened my own determination to act."
Prince William added: "Tonight, we celebrate far more than a remarkable milestone of 100 years.
"We celebrate a lifetime of extraordinary service. A life that has brought the natural world closer to humanity, and humanity closer to its responsibility to the natural world."
Meanwhile, video messages from a host of A-listers wishing Sir David a happy birthday were also played during the concert.
Dame Judi said: "Sir David, happy birthday, and how lucky we are to get this opportunity to thank you, for all the things that you've told us and taught us."
Actor DiCaprio added: "Thank you truly for everything you've done and continue to do, for our very precious planet and all its inhabitants."
Paddington Bear, Glastonbury chief Emily Eavis, actress Phoebe Waller-Bridge, singer Camila Cabello and composer Hans Zimmer also paid tribute to Sir David in pre-recorded birthday tributes.
Actress Olivia Colman said: "Thank you so much for everything you have given all of us throughout the years, the world is a much better place with you in it."
Coldplay frontman Chris Martin said the band "send you so much love and respect", while pop singer Raye said: "Your voice is a gift to this earth, you are a national treasure."
The BBC Concert Orchestra provided live, orchestral music throughout the night, soundtracking some of the most memorable sequences from Sir David's career.
They included the snakes and iguanas chase from Planet Earth II, and the seals vs orcas sequence from Frozen Planet II.
Later, the orchestra was joined by singer Smith for a live rendition of his band Bastille's hit Pompeii.
Icelandic rock band Sigur Rós also performed Hoppípolla, their 2005 song which has soundtracked countless wildlife programmes, as well as many others films, trailers, and advertisements.
Most of the night's musical performances were accompanied by archival footage or other montages celebrating Sir David's career.
Guests including wildlife presenters Liz Bonnin, Steve Backshall and Chris Packham also reflected on Sir David's impact on public policy - particular the reduction in plastic straw and plastic bag use following the broadcast of Blue Planet II.
Sir Michael recounted the story of how Sir David commissioned Monty Python when he was the controller of BBC Two.
The pair became friends, and Sir Michael reflected that Sir David's success is partly down to the fact that he always "just looks as though he's happy to be there".
"He wants to meet these people and see these animals," Sir Michael said. "It's not something he's been asked to do; it's something that fulfils him."
Elsewhere, Young invited the audience to sing Happy Birthday to Sir David, who appeared touched and grateful as he waved to the crowd.
As the concert began to draw to a close, the BBC announced that Sir David will soon narrate another new natural history series, Blue Planet III.
The night at the Royal Albert Hall concluded with a highlight montage from Sir David's career, soundtracked by his own delivery of the poignant lyrics to What A Wonderful World.
Young told him: "Thank you David, not just for joining us here tonight, but for sharing your knowledge and love of the planet. You've given nature a voice, and what a voice it is."
