Manuel Antonio Rosales Guerrero (born 12 December 1952, in Santa Bárbara del Zulia) is a Venezuelan educator and politician and former governor of Zulia. He was the most prominent Venezuelan opposition candidate in the 2006 presidential election, losing to incumbent Hugo Chávez. He served as a congressman, mayor, and governor, but in April 2009, stepped down as Mayor of Maracaibo when he was charged with corruption in Venezuela and fled to Peru. Rosales denies the charges, and was granted political asylum in Peru. He was briefly the presidential candidate for Un Nuevo Tiempo in the 2024 Venezuelan presidential election, but he ended up suspending his candidacy.

Rosales began his political career as a youth leader of the political party, Acción Democrática (AD), described by the BBC as "one of the two parties that dominated Venezuelan politics for most of the second half of the 20th Century". In 2000 he founded "his own centre-left party which he called Un Nuevo Tiempo" (A New Era); he describes "himself as a social democrat".

Rosales served as a congressman in the Zulia Legislative Assembly (1983–1994), Mayor of Maracaibo (1996–2000)—Venezuela's second-largest city, in Zulia, Venezuela's wealthiest state—and Governor of Zulia for two terms (2000–2004 and 2004–2008).

Rosales was accused of participating in the 2002 "attempt to oust the president"; according to the BBC, "government supporters accuse him of taking part in a short-lived coup ...". Rosales signed the Carmona Decree—a document drawn up on the day following the Venezuelan coup attempt of 2002, which saw the temporary removal of President Chávez. He declared that he signed during a "moment of confusion" after "Chavez's resignation, although [Chavez] later denied [the resignation]", and that he signed his attendance at a meeting he was urgently requested to attend.

Rosales was defeated by Chavez in the December 2006 Venezuelan election to choose a president for the six-year term beginning in January 2007. A primary election organized by Sumate had been scheduled for August 2006, but was cancelled when other presidential opposition candidates agreed to withdraw from the race and support Rosales. As "one of only two governors" opposed to Chavez, Rosales united the opposition, representing a broad coalition of parties and organizations opposed to Hugo Chávez. According to the BBC, "critics ... describe him as uncharismatic".

Rosales' platform was based on what he called "democracy and social justice" and crime; according to the BBC, "He has accused Mr Chavez of wasting the country's oil wealth on friendly governments abroad and of trying to introduce Cuban-style communism." Rosales said that the backbone of his government program would be the social arena, saying it would be a "sound and well defined" program, including a "fair allocation of oil revenues by means of two axes – minimum wage for all unemployed and direct contribution to the underprivileged". He stated that Chávez was vulnerable on his "massive foreign aid programs, government-approved takeovers of land and buildings, and the perception that crime is increasing". Rosales said, "We will distribute land to the peasants, but we will buy it in such a way as to respect the principle of private property, just as we will respect those of human rights and social justice." His platform would halt oil giveaways, "including sales of discounted oil to Cuba, until Venezuela reduced its high poverty rate."

Rosales accused Chávez of "overspending on a military buildup" and pledged "to use Venezuela's oil wealth to help the poor and improve education and health care", ridiculing Chávez's "claims of a possible war with the U.S." and saying, "Venezuela's real war should be against rampant street crime." The New York Times said, "Rosales has focused on other themes, including fierce criticism of the alliances Mr. Chávez has made with countries on the fringes of American influence, like Iran and Cuba. But his campaign's predominant message is that Mr. Chávez, despite his socialist talk, has failed to deliver oil wealth to the poor." The New York Times also said Rosales "has been pounding the crime issue, questioning why murders have surged since Mr. Chávez entered office", and saying Chavez's "confrontational style" was "feeding the crime epidemic".

Incumbent president Hugo Chávez was re-elected with 62.87% of the vote.