Prime Minister Tony Blair, Baroness Thatcher, Sir John Major, guitarist Eric Clapton and singers Sir Cliff Richard and Dame Vera Lynn gathered to pay their respects.
More than 2,300 people St Paul's Cathedral in London for the formal Christian service, attended by over 30 members of the Royal Family including the Duke of Edinburgh, the Prince of Wales and Princes William and Harry.
During her birthday speech, the Queen turned to the wit and wisdom of Groucho Marx at the national service of thanksgiving and a special birthday luncheon.
She told guests at the lunch: "As one gets older, birthdays seem to come round quicker; they are therefore less obviously excuses for wider celebration than personal moments to count one's blessings. As Groucho Marx once said 'Anyone can get old - all you have to do is to live long enough'."
The Archbishop of Canterbury praised the Queen in his sermon, saying a "common loyalty to the monarch" had helped keep the country together.In his sermon, Dr Rowan Williams said the monarchy had been a "way of keeping power human".
The Queen had been a "steady presence" in an "age of inhumanity of ideology and of myths of racial supremacy", he said.
Dr Williams said "the Holocaust and Stalinism and ethnic cleansing, fanaticism and terror and mass destruction" reminded us what a tough question it was to ask what gives cohesion to a society.
He said that among the things which achieved "such cohesion as we have" was loyalty to the monarch."We have seen something of a monarch who has shared the vulnerability of ordinary people, and that has been moving in itself," he said. "But more importantly we have been able to see a bit more clearly the personal depth of our monarch's faith."
The archbishop led thanks to the Queen and to Prince Philip "who has so devotedly supported you" and wished the couple many happy more years.
In tribute to her husband Philip and her eldest son Charles, the Queen thanked them both for "all the support they give me each and every day".
She said there were many other anniversaries more deserving of celebration than her birthday, singling out the 50th anniversary of the Duke of Edinburgh Award Scheme and the 30th anniversary of the Prince's Trust.
The Queen said she was aware of the value of the advice and encouragement she was lucky enough to receive from "every quarter - from my family, from my friends, from all of you". She described the thousands of goodwill messages she received from the public for her 80th as "truly overwhelming".
