Ion Heliade Rădulescu or Ion Heliade (also known as Eliade or Eliade Rădulescu; Romanian pronunciation: [ˈi.on (h)eliˈade rəduˈlesku]; 6 January 1802 – 27 April 1872) was a Wallachian, later Romanian academic, Romantic and Classicist poet, essayist, memoirist, short story writer, newspaper editor and politician. A prolific translator of foreign literature into Romanian, he was also the author of books on linguistics and history. For much of his life, Heliade Rădulescu was a teacher at Saint Sava College in Bucharest, which he helped reopen. He was a founding member and first president of the Romanian Academy.

Heliade Rădulescu is considered one of the foremost champions of Romanian culture from the first half of the 19th century, having first risen to prominence through his association with Gheorghe Lazăr and his support of Lazăr's drive for discontinuing education in Greek. Over the following decades, he had a major role in shaping the modern Romanian language, but caused controversy when he advocated the massive introduction of Italian neologisms into the Romanian lexis. A Romantic nationalist landowner siding with moderate liberals, Heliade was among the leaders of the 1848 Wallachian revolution, after which he was forced to spend several years in exile. Adopting an original form of conservatism, which emphasized the role of the aristocratic boyars in Romanian history, he was rewarded for supporting the Ottoman Empire and clashed with the radical wing of the 1848 revolutionaries.

Heliade Rădulescu was born in Târgoviște, into a family of Greek ancestry; he was the son of Ilie Rădulescu, a wealthy proprietor who served as the leader of a patrol unit during the 1810s, and Eufrosina Danielopol, a Greek woman, who was also educated in Greek. Three of his siblings died of bubonic plague before 1829. Throughout his early youth, Ion was the focus of his parents' affectionate supervision: early on, Ilie Rădulescu purchased a house once owned by the scholar Gheorghe Lazăr on the outskirts of Bucharest (near Obor), as a gift for his son. At the time, the Rădulescus were owners of a large garden in the Bucharest area, nearby Herăstrău, as well as of estates in the vicinity of Făgăraș and Gârbovi.

After basic education in Greek with a tutor known as Alexe, Ion Heliade Rădulescu taught himself reading in Romanian Cyrillic (reportedly by studying the Alexander Romance with the help of his father's Oltenian servants). He subsequently became an avid reader of popular novels, especially during his 1813 sojourn in Gârbovi (where he had been sent after other areas of the country came to be ravaged by Caragea's plague). After 1813, the teenaged Rădulescu was a pupil of the Orthodox monk Naum Râmniceanu; in 1815, he moved on to the Greek school at Schitu Măgureanu, in Bucharest, and, in 1818, to the Saint Sava School, where he studied under Gheorghe Lazăr's supervision.

Between his 1820 graduation and 1821, when effects of the Wallachian uprising led to the School ceasing its activities, he was kept as Lazăr's assistant teacher, tutoring in arithmetics and geometry. It was during those years that he adopted the surname Heliade (also rendered Heliad, Eliad or Eliade), which, he later explained, was a Greek version of his patronymic, in turn stemming from the Romanian version of Elijah.

In 1822, after Gheorghe Lazăr had fallen ill, Heliade reopened Saint Sava and served as its main teacher (initially, without any form of remuneration). He was later joined in this effort by other intellectuals of the day, such as Eufrosin Poteca, and, eventually, also opened an art class overseen by the Croat Carol Valştain. This re-establishment came as a result of ordinances issued by Prince Grigore IV Ghica, who had just been assigned by the Ottoman Empire to the throne of Wallachia upon the disestablishment of Phanariote rule, encouraging the marginalization of ethnic Greeks who had assumed public office in previous decades. Thus, Prince Ghica had endorsed education in Romanian and, in one of his official firmans, defined teaching in Greek as "the foundation of evils" (temelia răutăţilor).

During the late 1820s, Heliade became involved in cultural policies. In 1827, he and Dinicu Golescu founded Soțietatea literară românească (the Romanian Literary Society), which, through its program (mapped out by Heliade himself), proposed Saint Sava's transformation into a college, the opening of another such institution in Craiova, and the creation of schools in virtually all Wallachian localities. In addition, Soţietatea attempted to encourage the establishment of Romanian-language newspapers, calling for an end to the state monopoly on printing presses. The grouping, headquartered on central Bucharest's Podul Mogoșoaiei, benefited from Golescu's experience abroad, and was soon joined by two future Princes, Gheorghe Bibescu and Barbu Dimitrie Știrbei. Its character was based on Freemasonry; around that time, Heliade is known to have become a Freemason, as did a large section of his generation.

In 1828, Heliade published his first work, an essay on Romanian grammar, in the Transylvanian city of Hermannstadt (which was part of the Austrian Empire at the time), and, on 20 April 1829, began printing the Bucharest-based paper Curierul Românesc. This was the most successful of several attempts to create a local newspaper, something Golescu first attempted in 1828. Publishing articles in both Romanian and French, Curierul Românesc had, starting in 1836, its own literary supplement, under the title of Curier de Ambe Sexe; in print until 1847, it notably published one of Heliade's most famous poems, Zburătorul. Curierul Românesc was edited as a weekly, and later as a bimonthly, until 1839, when it began to be issued three or four times a week. Its best-known contributors were Heliade himself, Grigore Alexandrescu, Costache Negruzzi, Dimitrie Bolintineanu, Ioan Catina, Vasile Cârlova, and Iancu Văcărescu.