Béla I the Boxer or the Wisent (Hungarian: I. Bajnok or Bölény Béla, Slovak: Belo I.; c. 1015 – 11 September 1063) was King of Hungary from 1060 until his death. He descended from a younger branch of the Árpád dynasty. Béla's baptismal name was Adalbert. He left Hungary in 1031, together with his brothers, Levente and Andrew, after the execution of their father, Vazul. Béla settled in Poland and married Richeza (or Adelaide), daughter of Polish king Mieszko II Lambert.

He returned to his homeland upon the invitation of his brother Andrew, who had in the meantime been crowned King of Hungary. Andrew assigned the administration of the so-called ducatus or "duchy", which encompassed around one-third of the territory of the Kingdom of Hungary, to Béla. The two brothers' relationship became tense when Andrew had his own son, Solomon, crowned king, and forced Béla to publicly confirm Solomon's right to the throne in 1057 or 1058. Béla, assisted by his Polish relatives, rebelled against his brother and dethroned him in 1060. He introduced monetary reform and subdued the last uprising aimed at the restoration of paganism in Hungary. Béla was fatally injured when his throne collapsed while he was sitting on it.