Tiziano Vecellio (Italian: [titˈtsjaːno veˈtʃɛlljo]; c. 1488/1490 – 27 August 1576), Latinized as Titianus, hence known in English as Titian (/ˈtɪʃən/ ^ⓘ TISH-ən), was an Italian Renaissance painter. The most important artist of Renaissance Venetian painting, he was born in Pieve di Cadore, near Belluno.

Titian was one of the most versatile of Italian painters, equally adept with portraits, landscape backgrounds, and mythological and religious subjects. His painting methods, particularly in the application and use of colour, exerted a profound influence not only on painters of the late Italian Renaissance, but on future generations of Western artists.

His career was successful from the start, and he became sought after by patrons, initially from Venice and its possessions, then joined by the north Italian princes, and finally the Habsburgs and the papacy. Along with Giorgione, he is considered a founder of the Venetian school of Italian Renaissance painting. In 1590, the painter and art theorist Giovanni Paolo Lomazzo described Titian as "the sun amidst small stars not only among the Italians but all the painters of the world".

During his long life, Titian's artistic manner changed drastically, but he retained a lifelong interest in colour. Although his mature works may not contain the vivid, luminous tints of his early pieces, they are remarkable and original in their loose brushwork and subtlety of tone.

The exact date of Titian's birth is uncertain. When he was an old man he claimed in a letter to Philip II of Spain to have been born in 1474, but this seems most unlikely. Other writers contemporary to his old age give figures that would equate to birth dates between 1473 and after 1482. Although his age at death being 99 was still accepted into the 20th century, most modern scholars believe a birth date between 1488 and 1490 is likeliest.

He was the son of Gregorio Vecellio and his wife Lucia, of whom little is known. The Vecellio family was well established in the area, which was ruled by Venice. Titian's grandfather Conte Vecellio was a prominent notary who held a number of offices in the local administration. Three of Conte's sons were notaries, not including Gregorio, who was active as a soldier and closely associated with the Venetian Arsenal, but worked mainly as a timber merchant and also managed mines in the mountainous Cadore region for their owners.

Ludovico Dolce, who knew Titian, says that Titian had four masters, the first being Sebastiano Zuccato, the second Gentile Bellini, then his brother Giovanni Bellini, and last, Giorgione. No documentation for these relationships has been found. The Zucatti family of artists are best known as mosaicists, but there is no evidence that the painter Sebastiano Zuccato himself was active as a mosaicist, although Joannides says he probably was.

According to Giorgio Vasari, who also knew Titian and included a not always accurate biography of the artist in his Lives, Titian first studied under Giovanni Bellini. Dolce writes that the boy was sent to Venice at age nine, along with his brother Francesco, to live with an uncle and apprentice to Sebastiano Zuccato. Leaving Zuccato, Titian briefly transferred to the studio of Gentile Bellini, one of the largest and most productive workshops in Venice. Following Gentile's death in 1507 he entered into an apprenticeship with Gentile's younger brother Giovanni, acknowledged by contemporaries as the preeminent Venetian painter of the day. As there is no documentation of Titian's work before 1510, there is no way to know which version, Dolce's or Vasari's, is closer to the truth. Living in the city, Titian found a group of young men about his own age, among them Giovanni Palma da Serinalta, Lorenzo Lotto, Sebastiano Luciani, and Giorgio da Castelfranco, nicknamed Giorgione. Francesco Vecellio, Titian's brother, while more workmanlike in his approach to painting and lacking Titian's talent, was able to achieve some notice in his home town of Cadore and the Bellunese area around it.