Honório Hermeto Carneiro Leão, Marquis of Paraná

Honório Hermeto Carneiro Leão, Marquis of Paraná (11 January 1801 – 3 September 1856) was a Brazilian politician, diplomat, judge and monarchist. Paraná was born to a family of humble means in São Carlos do Jacuí, in what was then the captaincy of Minas Gerais. After attending the University of Coimbra in Portugal and having returned to Brazil, Paraná was appointed a judge in 1826 and later elevated to appellate court justice. In 1830, he was elected to represent Minas Gerais in the Chamber of Deputies; he was re-elected in 1834 and 1838, and held the post until 1841.

In the aftermath of emperor Pedro I's abdication in 1831, a regency created to govern Brazil during the minority of the former emperor's son, Pedro II, soon dissolved into chaos. Paraná formed a political party in 1837 that became known as the Reactionary Party, which evolved into the Party of Order in the early 1840s and in the mid-1850s into the Conservative Party. He and his party's stalwart and unconditional defence of constitutional order allowed the country to move beyond a regency plagued by factious disputes and rebellions that might easily have led to a dictatorship. Appointed president of Rio de Janeiro Province in 1841, Paraná helped put down a rebellion headed by the opposition Liberal Party the following year. Also in 1842, he was elected senator for Minas Gerais and appointed by Pedro II to the Council of State. In 1843, he became the de facto first president (prime minister) of the Council of Ministers, but resigned after a quarrel with the emperor.

After years in opposition, in 1849, Paraná was appointed by the national government as president of Pernambuco Province to investigate a Liberal rebellion that had taken place a year earlier, and seek a fair trial for the rebels. Blamed by his party colleagues for the years in opposition and having lost much of his influence within his own party, Paraná accepted the post, believing he could regain his place among his peers. With the nation internally pacified, he was sent to Uruguay in 1851 to forge an alliance with that country, and with the rebel Argentine provinces of Corrientes and Entre Ríos, against the Argentine Confederation. The alliance triumphed, and the emperor elevated Paraná to the ranks of the titled nobility.

In 1853, Paraná was again appointed president of the Council of Ministers, at the head of a highly successful cabinet, and became the most powerful politician in the country. The electoral reform he ushered in was credited with undermining national political processes and causing severe harm to the system of parliamentary government. For his role in pushing through restructuring, Paraná met with fierce opposition from the majority of his colleagues, leading to a virtual split in the Conservative Party over his policies. On 3 September 1856, while still in office and at the height of his political career, he died unexpectedly of an unknown febrile condition. He is widely regarded by historians as one of the most influential statesmen of his time.