Bayezid I, known as Yıldırım (the thunderbolt) was the fourth Ottoman sultan. He is known for his military prowess, as well as for establishing the first version of a centralized Ottoman empire, which nevertheless collapsed again after his death in 1403/805 AH.
Sources:
Halil Inalcik, "Bāyazīd," in Encyclopaedia of Islam, Second Edition, edited by P. Bearman et al. http://dx/doi.org/10.1163/1573-3912_islam_SIM_1302 (accessed April 20, 2018).
