"Like many of my contemporaries I am in politics because of Margaret Thatcher.
"Although I did not share her political outlook, as our first female Prime Minister she changed the face of our political system forever.
"While in many respects she was divisive, Margaret Thatcher was undoubtedly the leading political figure of her generation.
"Her impact on British politics and our country was substantial and enduring."
Thoughts + prayers of all Americans w Lady Thatcher's family + British people - a towering figure in British life who will be missed by many
Sinn Fein leader Gerry Adams has criticised Lady Thatcher, saying "her Irish policy failed miserably":
Margaret Thatcher did great hurt to the Irish and British people during her time as British Prime Minister.
Working class communities were devastated in Britain because of her policies.
Her role in international affairs was equally belligerent whether in support of the Chilean dictator Pinochet, her opposition to sanctions against apartheid South Africa; and her support for the Khmer Rouge.
Here in Ireland her espousal of old draconian militaristic policies prolonged the war and caused great suffering.
Margaret Thatcher will be especially remembered for her shameful role during the epic hunger strikes of 1980 and ’81.
Her Irish policy failed miserably.
Rob Harris, a reporter for The Associated Press, says the Premier League will not be asking clubs to hold a minute's silence for Margaret Thatcher.
Former Number 10 spin chief Alastair Campbell wrote on Twitter:
disagreed with much she did but Mrs Thatcher was one hell of a PM to cover as a journalist, and one of small number of real change PMs
Former US President George Bush paid tribute to former Prime Minister Margaret Thatcher, saying she was an "inspirational leader" and a "great example of strength and character."
Laura and I are saddened by the death of Baroness Margaret Thatcher. She was an inspirational leader who stood on principle and guided her nation with confidence and clarity.
Prime Minister Thatcher is a great example of strength and character, and a great ally who strengthened the special relationship between the United Kingdom and the United States.
Laura and I join the people of Great Britain in remembering the life and leadership of this strong woman and friend.
Today represents a great loss for our country. Margaret Thatcher was greatest PM of post-war era. A privilege and honour to have known her.
First Minister Alex Salmon has paid tribute to Baroness Thatcher.
"Margaret Thatcher was a truly formidable prime minister whose policies defined a political generation.
“No doubt there will now be a renewed debate about the impact of that legacy.
“Today, however, the proper reaction should be respect and condolences to her family."