Comedian Sacha Baron Cohen and his wife actress Isla Fisher have donated more than £670,000 to charity.
The couple have given 500,000 dollars (£336,000) to Save The Children to help vaccinate against a potential measles outbreak in northern Syria that threatens 250,000 children.
Baron Cohen, 44, and Fisher, 39 are also giving a separate sum of 500,000 dollars to the New York-based International Rescue Committee which is run by former foreign secretary David Miliband.
That donation will go towards education, health care, shelter and sanitation for refugees in Syria and neighbouring countries, with a special focus on women and children.
Currently four million Syrians are living as refugees in neighbouring countries and over seven million are displaced inside Syria. It has been estimated that around 12,000 children have been killed since the conflict began.
Justin Forsyth, chief executive of Save The Children, said their donation would "save many thousands of lives".
He said: "The Syrian conflict is now approaching its fifth year and children are the first victims. There is no safe place left in Syria, with shelling and violence omnipresent. Food and medicines have become scarce and basic necessities unaffordable. Syria's health system has collapsed and deadly childhood diseases - like measles - which had previously been all but eradicated have now returned, threatening the lives of hundreds of thousands of children.
"By allowing us to make their generous donation to Syrian children public, Sacha and Isla are helping highlight the tragedy of the issue today. These are desperate times for Syrian families facing bombs, bullets and torture in Syria. The couple's donation will save many thousands of lives and protect some of the most vulnerable children."
Mr Miliband added: "Now is the time for all of us to double down on commitments to civilians caught up in the Syria conflict. These people are the victims of terror. As hope for the end of conflict recedes, it is all the more important to meet the most basic human needs.
"Sacha and Isla's donation is a great expression of humanity, and a challenge to do more for the most vulnerable. I hope it is an example to many others seeking practical ways of making a difference during the Christmas and New Year season."
Baron Cohen is known for creating characters including Borat and Ali G, while Fisher has appeared in Australian soap Home And Away and films including Wedding Crashers.
The pair share three children: daughters Olive and Elula, and a son called Montgomery, who was born in March this year.