Alcalde ( /ælˈkældi/; Spanish: [alˈkalde]), or Alcalde ordinario, is the traditional Spanish municipal magistrate, who had both judicial and administrative functions. An alcalde was, in the absence of a corregidor, the presiding officer of the Castilian cabildo (the municipal council) and judge of first instance of a town. Alcaldes were elected annually, without the right to reelection for two or three years, by the regidores (council members) of the municipal council. The office of the alcalde was signified by a staff of office, which they were to take with them when doing their business.

The office of the alcalde evolved during the Reconquista as new lands were settled by the expanding kingdoms of León and Castile. As fortified settlements in the area between the Duero and Tagus rivers became true urban centers, they gained, from their feudal lords or the kings of Leon and Castile, the right to have councils. Among the rights that these councils had was to elect a municipal judge (iudex in Latin and juez in Spanish). These judges were assisted in their duties by various assistant judges, called alcaldes, whose number depended on the number of parishes the town had. The title alcalde was borrowed from the Arabic al-qaḍi ( قاضي,), meaning "the judge." The word alcalde originally was used for simple judges, as in Andalusian Arabic. Only later was it applied to the presiding municipal magistrate. This early use continued to be reflected in its other uses—such as in alcaldes del crimen, the judges in the audiencias; Alcaldes de la Casa y Corte de Su Majestad, who formed the highest tribunal in Castile and also managed the royal court; alcaldes mayores (a synonym for corregidor); and alcaldes de barrio, who were roughly the equivalent of the British parish constables. Because of this, the municipal alcalde was often referred to as an alcalde ordinario.

Gustavo Francisco Petro Urrego (born 19 April 1960) is a Colombian politician of the Political Independent movement Progresistas (Progressivists) and the current Mayor of Bogotá. As a young man he became and active member of the 19th of April Movement, which later evolved into the Alianza Democrática M-19, a political party in which Petro also participated. Years later he would become the presidential candidate of the Alternative Democratic Pole in the 2010 Colombian election, but lost at ranking fourth after the now President Juan Manuel Santos, Antanas Mockus and German Vargas Lleras respectively. After departing of the Pole in 2010, Petro was elected mayor of Bogota in the Colombian regional elections of 2011.

Petro studied at the Colegio de Hermanos de La Salle, where he founded the student newspaper Carta al Pueblo ("Letter to the People"). At the age of 18 he became a member of the 19th of April Movement, and was involved in military and political activities. During his time in 19 April Petro became a popular leader, and was elected ombudsman of Zipaquirá in 1981 and councilman from 1984 to 1986.