Ludovico Ariosto (UK: /æriˈɒstoʊ/, US: /ɑːriˈ-/; Italian: [ludoˈviːko aˈrjɔsto, - ariˈɔsto]; 8 September 1474 – 6 July 1533) was an Italian poet. He is best known as the author of the romance epic Orlando Furioso (1516-1532). The poem, a continuation of Matteo Maria Boiardo's Orlando Innamorato, describes the adventures of Charlemagne, Orlando, and the Franks as they battle against the Saracens with diversions into many sideplots. The poem is transformed into a satire of the chivalric tradition. Ariosto composed the poem in the ottava rima rhyme scheme and introduced narrative commentary throughout the work.

Ariosto also coined the term "humanism" (in Italian, umanesimo) for choosing to focus upon the strengths and potential of humanity, rather than only upon its role as subordinate to God. This led to Renaissance humanism.

Ariosto was born in Reggio nell'Emilia, where his father Niccolò Ariosto was commander of the citadel. He was the oldest of 10 children and was seen as the successor to the patriarchal position of his family. From his earliest years, Ludovico was very interested in poetry, but he was obliged by his father to study law.

After five years of law, Ariosto was allowed to read classics under Gregorio da Spoleto. Ariosto's studies of Greek and Latin literature were cut short by Spoleto's move to France to tutor Francesco Sforza. Shortly after this, Ariosto's father died.

After the death of his father, Ludovico Ariosto was compelled to forgo his literary occupations and take care of his family, whose affairs were in disarray. Despite his family obligations, Ariosto managed to write some comedies in prose as well as lyrical pieces. Some of these attracted the notice of Cardinal Ippolito d'Este, who took the young poet under his patronage and appointed him one of the gentlemen of his household. Este compensated Ariosto poorly for his efforts; the only reward he gave the poet for Orlando Furioso, dedicated to him, was the question, "Where did you find so many stories, Master Ludovico?" Ariosto later said that the cardinal was ungrateful, that he deplored the time which he spent under his yoke, and that if he received some small pension, it was not to reward him for his poetry – which the prelate despised – but for acting as a messenger.

Ludovico Ariosto and Leonardo da Vinci shared a patron in Cardinal Ippolito d'Este's older sister the Marchioness Isabella d'Este, the "First Lady of the Renaissance." Isabella d'Este appears in Ludovico's masterpiece, Orlando Furioso. She also appears in Leonardo's Sketch for a Portrait of Isabella d'Este at the Louvre.

A statue no less jocund, no less bright,
Succeeds, and on the writing is impressed;
Lo! Hercules' daughter, Isabella hight,
In whom Ferrara deems city blest,
Much more because she first shall see the light
Within its circuit, than for all the rest
Which kind and favouring Fortune in the flow
Of rolling years, shall on that town bestow.

— Orlando Furioso, Canto XLII.