Veteran Algerian diplomat Lakhdar Brahimi is the new UN / Arab League envoy for Syria.
He will succeed Kofi Annan, who resigned earlier this month after his peace plan failed.
A former UN envoy in Afghanistan and Iraq, Mr Brahimi also negotiated the end of Lebanon's civil war.
Mr Brahimi, 78, has held a long series of high-profile diplomatic posts.
As a senior Arab League official between 1984-91, he brokered an end to the Lebanese civil war, going on to serve as Algerian foreign minister between 1991-3.
Later, he was twice appointed as the UN's top envoy for Afghanistan, from 1996-8 and from 2001-4.
He has held similar roles for Haiti and South Africa.
Mr Brahimi told the BBC that peace efforts must continue:
''I might very well fail but we sometimes are lucky and we can get a breakthrough,'' he said.
''These missions have to be undertaken. We have got to try, We have got to see that the Syrian people are not abandoned.''
In an interview with France 24 news channel, Mr Brahimi was asked if he was confident the civil war could be ended.
''No I'm not,'' he replied. ''What I am confident of is that I am going to try my utmost, my very, very best.''