Bayajidda (Hausa with tone markings: Bàyā̀jiddà) (real name: Abu Yazid) was, according to the legends surrounding most West African states before the 19th century, the founder of the Hausa states.

Most accounts say that Bayajidda came from Baghdad. Bayajidda came first to Borno where he was given one of the Mai's daughters as a wife, and then later lived for a while in Hausa land where he married Daurama Shawata, the Queen of Daura, who also gave him a Gwari mistress as a reward for slaying "Sarki", said to be a great snake which deprived her people of access to water. By the Queen of Daura, Bayajidda had a son called Bawo, another called Biram by the Borno princess, and yet another son, Karbagari, by his Gwari paramour. Bawo is said to have succeeded his father and had six sons who became the rulers of Daura, Katsina, Zazzau, Gobir, Kano and Rano. These, together with Biram, which was ruled by the son of Bayajidda and of the Borno Princess, formed the "Hausa Bakwai" or the "Hausa 7". However, Karbagari the son of the Gwari mistress had seven sons too who ruled Kebbi, Zamfara, Gwari, Jukun, Ilorin, Nupe and Yauri which are referred to in this tradition as the "Banza Bakwai" or "Vain 7"

According to the legend, Bayajidda was a prince from Baghdad (the capital of modern-day Iraq) and son of King Abdullahi, but he was exiled from his home town after Queen Zidam, also known as Zigawa, had conquered the city. Once he left Baghdad, he traveled across Africa with numerous warriors and arrived in Borno.

Once in Borno, tales differ as to what caused tension with the local king. According to one story, Bayajidda realized his forces were stronger than those of the king; because of this, he planned to overthrow him. However, the king heard of the plot and, after consulting with his advisors, gave Bayajidda his daughter, Magaram (also known as Magira), in marriage. Later, when the king attacked and took over several towns, he tricked his new son-in-law into leaving his own men to guard the towns, thereby decreasing the number of men Bayajidda had at his disposal. Bayajidda realized that he was being tricked when he had only his wife and one slave left; during the night, they fled to Garun Gabas, now situated in the Hadeja region. While there, Magaram gave birth to Bayajidda's first child, Biram, the eponymous ancestor of the petty kingdom of Gabas-ta-Biram ("east of Biram").

However, according to another version of the story, Bayajidda was welcomed into Borno, married Magaram and became popular among the people. Because of this, the king envied him and plotted against him; upon being informed of this by his wife, he fled Borno with her.

Bayajidda left his wife and child in Garun Gabas and continued on to the village of Gaya near Kano - which others believe to be Gaya in modern Niger -, where he had the local blacksmiths make him a knife. He then came to the town of Daura (located in modern-day Katsina State), where he entered a house and asked an old woman for water. She informed him that a serpent named Sarki (sarki is the Hausa word for king) guarded the well and that the people were only allowed to draw water once a week. Bayajidda set out for the well and killed the serpent with the sword and beheaded it with the knife the blacksmiths had made for him, after which he drank the water, put the head in a bag, and returned to the old woman's house. (The Kusugu Well where this is said to have happened is nowadays a tourist attraction.)

The next day, the people of Daura gathered at the well, wondering who had killed the snake; Magajiya Daurama, the local queen, offered sovereignty over half the town to whoever could prove that he killed the snake. Several men brought snake heads forth, but the heads did not match the body. The old woman, owner of the house Bayajidda was staying in, informed the queen that her guest had slayed it, after which Daurama summoned Bayajidda. Having presented the snake's head, proving to her that he was the one who had slain Sarki, he turned down the offer of half the town, instead requesting her hand in marriage; she married him out of gratitude for slaying the serpent.

Because it was against the custom of the people of Daura for their queens to marry, Daurama made a compromise with Bayajidda and said she would only have sexual intercourse with him later; because of this, she gave him a concubine named Bagwariya. (According to the oral palace version of the legend, Daurama gave him Bagwariya because she wanted to break her "queenly vow to remain a virgin," but had to undergo rituals to do so.)