Radama I "the Great" (c. 1793–1828) was the first Malagasy sovereign to be recognized as King of Madagascar (1810–1828) by a European state, Great Britain. He came to power at the age of 17 following the death of his father, King Andrianampoinimerina.

Under Radama's rule and at his invitation, the first Europeans entered his central highland Kingdom of Imerina and its capital at Antananarivo. Radama encouraged these London Missionary Society envoys to establish schools to teach tradecraft and literacy to nobles and potential military and civil service recruits. They also introduced Christianity and taught literacy using the translated Bible.

A wide range of political and social reforms were enacted under Radama's rule, including an end to the international slave trade, although this had historically been a key source of wealth and armaments for the Merina monarchy. Through aggressive military campaigns he successfully united two-thirds of the island under his rule. Abuse of alcohol weakened his health and he died prematurely at age 35. He was succeeded by his highest-ranking wife, Ranavalona I.

Radama was the son of Rambolamasoandro and King Andrianampoinimerina of Imerina, a growing kingdom in the central plateau of the island around Antananarivo. As a child, Radama was educated at court and learned to read the Malagasy language in the Sorabe Arabico-Malagasy script used by Antemoro ombiasy (court astrologers). As a young man he was described by a contemporary as about 5 ft 4 in (1.63 m) and slim with broad shoulders and a narrow waist.

Radama was invited to join his father on a military expedition during his campaign to pacify the Betsileo, who had forsaken an oath sworn to Andrianampoinimerina. Their initial attempt to capture King Andriamanalina at the fortified city of Fandanana west of Antsirabe was unsuccessful. When they returned a year later, Andrianampoinimerina split his army into two columns and put Radama at the head of the second column, providing him with his first opportunity to command a military regiment. He was accompanied by a group of seasoned soldiers called the Tantsaha, and Andriandtsoanandria, one of his father's more experienced military advisers. He successfully negotiated the submission of several towns in Betsileo.

Andrianampoinimerina ultimately captured and executed Andriamanalina, and together Radama and his father also captured the strategic town of Kiririoka. On Andrianampoinimerina's deathbed, he reportedly told his son, "The sea is the border of my rice field". Radama swore to his father that he would achieve this ambition.

In 1810, at the age of 17, Radama succeeded his father as king of Imerina. Several of the principalities conquered by his father revolted upon news of Andrianampoinimerina's death. The young ruler immediately had to embark on military campaigns that successfully put down the rebellions and secured his position, which included completing the pacification of the Betsileo kingdom.

In 1816 Radama was contacted in Mahazoarivo by Chardenoux, a Mauritian trader sent by British Governor Robert Townsend Farquhar of Mauritius (Ile de France), who was interested in increasing British influence in the region and preventing the re-establishment of French trading posts on Madagascar. As a result of this initial contact, two of Radama's half-brothers, Rahovy and Ramarotafika, were sponsored to be educated in Mauritius. This was followed by a commercial treaty.