Profile: José Luis Rodríguez Zapatero is only 42, the same age as the outgoing prime minister, José María Aznar, when he came to office in 2000, though a little older that the last incoming Socialist Party prime minister, Felipe González, in 1982.
Spain's electorate seems to go for new leaders as young as the country's democracy itself.
Mr Zapatero is an enigma, even to his closest associates, but unlike the stiff and self-righteous-seeming Mr Aznar, he is a man whom it is very difficult to dislike. He smiles a lot, and his eyes have a slightly messianic gleam, disturbingly reminiscent of Tony Blair's. That, however, may be all that Mr Zapatero has in common with the European centre-left leader to whom he is most often, and misleadingly, compared. Their radically opposed positions on the Iraq war are reflected in other areas.
The Spanish Socialist Workers' Party (PSOE) is not the British Labour Party. There is no traditionalist trade union leadership to confront and dismantle, or rather, that job has already been done by Felipe González. Mr Zapatero's biggest internal challenge comes from the regional party barons of the González era, a period when the party became notorious for croneyism and corruption.
Many doubts have been expressed as to whether this personable and charming new leader - this was his first general election - has really got these difficult men under control. And if he can't control his own party, his critics say, how can he cope with the massive challenges facing Spain: terrorism from within and without, a foreign policy crisis over Iraq, moves towards independence in the Basque Country and Catalonia, and coping with immigration, to name just a few.
Until last Sunday night, he seemed too consensual in his political style, just too damn nice, to cut the mustard as a prime minister. And yet, faced with the dramatically bittersweet moment of acknowledging a surprise election victory while 200 of his fellow citizens lay in morgues or premature graves, he looked and sounded like a statesman. Generous and compassionate, yes, but also strong, calm and totally in charge. Cometh the hour, cometh the man? Perhaps.
He was born in Vallodolid, a deeply traditional Castillian and Catholic city still associated, somewhat unfairly, with the Spanish far right. He comes from the other of "two Spains" which dominated the 20th century, the republican, secular, and leftist camp. His father reared him on stories of his grandfather, who was executed by Franco's insurgents.
He has never, however, been known to say a bitter word, about this or any other matter.
In opposing the Iraq war, though, he began to come into his own, without ever losing his even temper. It may be that his very mildness has gradually won over many Spaniards weary of Mr Aznar's hectoring style.
Trained as a constitutional lawyer, he has spent almost his entire adult life in professional politics. He is devoted to his wife, Sonsoles Espinosa, and his two pre-teen daughters, Laura and Alba.
To those who remember the hubris, massive graft, and state terrorism of the González years, the most disturbing thing about Mr Zapatero is that he has always wanted to emulate his charismatic but rather sinister predecessor, and that Mr González is said to reciprocate the admiration. But Mr Zapatero starts with a refreshingly clean sheet, and one must hope he will be able to keep it that way.