Frederick I of Baden, a member of the House of Zähringen, was Margrave of Baden and of Verona, as well as claimant Duke of Austria from 1250 until his death. As a fellow campaigner of the Hohenstaufen king Conradin, he likewise was beheaded at the behest of King Charles I of Naples.
He was born in Austrian Alland, the only son of the Swabian margrave Herman VI of Baden and his wife Gertrude, niece and heiress of the late Babenberg duke Frederick II of Austria.
As Duke Frederick II of Austria had been killed at the 1246 Battle of the Leitha River, the ducal line of the Babenberg dynasty had become extinct. Margrave Herman VI of Baden, through his marriage with Gertrude, had raised inheritance claims to the Austrian and Styrian possessions. However, after the death of Emperor Frederick II in 1250, no strong Imperial authority existed to assert his title. Though he was backed by Pope Innocent IV and anti-king William of Holland, Herman could not prevail against the claims raised by the mighty Přemyslid king Wenceslaus I of Bohemia and his warlike son Ottokar II.
At the time of the death of his father, young Frederick stayed at the Meissen court, where his mother Gertrude had fled. He could succeed Margrave Herman in Baden, with his uncle Rudolf I acting as regent. Also claimant to the Austrian and Styrian duchies through his mother, Frederick took his residence near Vienna. However, when in 1252 Ottokar II married Gertrude's aunt Margaret and moved into Austria, he again had to flee, at first to Styria and later to the Sponheim court in Carinthia.
From about 1266, Frederick grew up at the Wittelsbach residence of Duke Louis II of Bavaria, where he became friends with Conradin, Duke of Swabia, the young son of King Conrad IV of Germany and heir to the Imperial Hohenstaufen dynasty. From him Frederick expected support in enforcing his claims to power.
In 1267 he made the fatal decision to accompany Conradin on his expedition against Charles of Anjou, who had been crowned King of Sicily by Pope Clement IV and killed Conradin's uncle Manfred in the 1266 Battle of Benevento. Conradin had moved into Rome on 24 July 1268, however, Charles decisively defeated the Hohenstaufen troops at the Battle of Tagliacozzo on 23 August, whereafter Conradin and Frederick fled and passed into captivity on 8 September at Torre Astura, south of Anzio. Betrayed and handed over to King Charles by their Frangipani followers, both remained in degrading imprisonment at Castel dell'Ovo in Naples. The king himself condemned them to death; according to legend, they heard their verdict while playing chess and ineffectedly continued the game. Conradin and Frederick were publicly beheaded in the Piazza del Mercato on 29 October.