According to legend, there were twenty-eight Vyasas before the present Vyasa, Krishna Dvaipayana, born at the end of the Dvapara Yuga to Rishi Parashar and Satyavati Devi, a fisherman's daughter. Sage Parashar, a preeminent astrologer, foresaw that a child conceived at a particular auspicious time would become an incarnation of Lord Vishnu himself.
Origin Story: According to the Vishnu Purana, Vyasa was born on an island in the Yamuna River near the town of Kalpi. Upon reaching adulthood he left home, promising his mother he would return whenever she needed him, and gained spiritual wisdom from teachers including the four Kumaras, Devarishi Narada, and Lord Brahma. He was born already knowledgeable in the Vedas, Dharmashastras, and Upanishads.
Family: When his mother Satyavati's two sons by King Shantanu died without heirs, Vyasa fathered Dhritarashtra and Pandu through the widowed queens Ambika and Ambalika - along with a third son, Vidura. This made Vyasa the grandfather of both warring families of the Mahabharata, the Kauravas and the Pandavas, and a wise spiritual guide to the young princes.
Contributions: Vyasa was the first sage to compile and write down the Vedic knowledge that had until then existed only orally, systematically arranging the Vedas for humanity's benefit. He composed the Brahma Sutras, central to Vedanta, and is best known for compiling the epic Mahabharata - at nearly 100,000 verses and 1.8 million words, the longest known epic poem in any language.
A well-known legend recounts that Vyasa enlisted Lord Ganesha as his scribe for the Mahabharata: Ganesha agreed to write only if Vyasa recited without pause, and Vyasa in turn required Ganesha to understand each verse before writing it. When Ganesha's writing instrument broke mid-dictation, he snapped off one of his own tusks to continue - which is why Ganesha is called Ekdanta, "One-Tusked".
Legacy: Vyasa's final great work was the Bhagavata Purana, undertaken at the urging of Devarishi Narada. He is revered as a Chiranjivi, a sage believed to be eternally alive, appearing before sincere devotees - it is said that Adi Shankaracharya once saw Vyasa in the home of Sage Mandan Mishra. Vyasa remains a compassionate protector, living eternally for humanity's well-being.