Herut (Hebrew: חֵרוּת, lit. 'Freedom') was the major conservative nationalist political party in Israel from 1948 until its formal merger into Likud in 1988. It was an adherent of Revisionist Zionism. In 1948, Hannah Arendt and other Jewish intellectuals wrote a letter declaring that some of their policies were comparable to those of fascism.

Herut was founded by Menachem Begin on 15 June 1948 as a successor to the Revisionist Irgun, a militant group in Mandate Palestine. The new party was a challenge to the Hatzohar party established by Ze'ev Jabotinsky. Herut also established an eponymous newspaper, with many of its founding journalists defecting from Hatzohar's HaMashkif.

Objection to withdrawal of the Israel Defense Forces (IDF) and negotiations with Arab states formed the party's main platform in the first Knesset election. The party vigorously opposed the ceasefire agreements with the Arab states until the annexation of Gaza Strip and the West Bank, both before and after the election. Herut differentiated itself by refusing to recognise the legitimacy of the Kingdom of Jordan after the armistice, and frequently used the slogan "Two banks of the Jordan River" in claiming Israel's right to the whole of Eretz Israel/Palestine because of their historical significance in religious Jewish texts. According to Joseph Heller, Herut was a one-issue party intent on expanding Israel's borders.

Herut's socio-economic platform represented a clear shift to the right, with support for private initiative, but also for legislation preventing the trusts from exploiting workers. Begin was at first careful not to appear anti-socialist, stressing his opposition to monopolies and trusts, and also demanding that "all public utility works and basic industries must be nationalized". Herut was from the outset inclined to sympathise with the underdog, and, according to Hannah Torok Yablonka, "tended to serve as a lodestone for society's misfits".

Herut's political expectations were high as the first election approached in 1949. It took credit for driving the British government out and as a young movement, reflecting the esprit of the nation, it perceived its image as being more attractive than the old establishment. They hoped to win 25 seats, which would place them second and make them leader of the opposition, with potential for a future gain of government power. This analysis was shared by other parties. At the elections, Herut only won 14 seats with 11.5 percent of the votes, making it the fourth-largest party in the Knesset; Hatzohar, on the other hand, failed to cross the electoral threshold of 1 percent and disbanded shortly thereafter.^{[citation needed]}

Though practical differences between the two parties were less dramatic than the rhetoric suggested, both the Labor Zionist establishment and the opposition Herut emphasised those differences to mobilise their voters.

The hostility between Begin and Israel's first Prime Minister, the Mapai leader David Ben-Gurion, which had begun over the Altalena Affair, was evident in the Knesset. Ben-Gurion coined the phrase "without Herut and Maki" (Maki was the Communist Party of Israel), a reference to his position that he would include any party in his coalition, except those two. In fact, Herut was approached at least three times (1952, 1955, and 1961) by Mapai for government negotiations; Begin turned down each offer, suspecting that they were designed to divide his party. The ostracism also expressed itself in the Prime Minister's refusal to refer to Begin by name from the Knesset Podium, using instead the phrase "the person who sits next to M. K. Badar", and boycotting his Knesset speeches.

Ben-Gurion's policy of ostracising Revisionism was performed systematically, as seen in the legal exclusion of fallen Irgun and Lehi fighters from public commemoration and from benefits to their families. Herut members were excluded from the highest bureaucratic and military positions.