Henry IV (November 11, 1050 — 1106) was King of Germany from 1056 and Emperor from 1084, until his abdication in 1105. He was the third emperor of the Salian dynasty.

Henry was the eldest son of the Emperor Henry III, by his second wife Agnes de Poitou, and was probably born at the royal palace at Goslar. His christening was delayed until the following Easter so that Abbot Hugh of Cluny could be one of his godparents. But even before that, at his Christmas court Henry III induced the attending nobles to promise to be faithful to his son. Three years later, still anxious to insure the succession, Henry III had a larger assembly of nobles elect the young Henry as his successor, and then, on July 17, 1054, had him crowned as king by Archbishop Herman of Cologne. Thus when Henry III unexpectedly died in 1056, the accession of the 6-year-old Henry IV was not opposed. The dowager Empress Agnes acted as regent. Henry's reign was marked by efforts to consolidate Imperial power. In reality, however, it was a careful balancing act between maintaining the loyalty of the nobility and the support of the pope. Henry jeopardized both when, in 1075, his insistence on the right of a secular ruler to invest, i.e., to place in office, members of the clergy, especially bishops, began the conflict known as the Investiture Controversy. Pope Gregory VII excommunicated Henry on February 22, 1076. Gregory, on his way to a diet at Augsburg, and hearing that Henry was approaching, took refuge in the castle of Canossa (near Reggio Emilia), belonging to Matilda, Countess of Tuscany. Henry's intent, however, was to perform the penance required to lift his excommunication, and ensure his continued rule. He stood for three days, January 25 to January 27, 1077, outside the gate at Canossa, begging the pope to rescind the sentence (though not, as is often stated, in bare shirt with no food or shelter). The Pope lifted the excommunication, imposing a vow to comply with certain conditions, which Henry soon violated.

Henry's first marriage, to Bertha, countess of Maurine, produced two sons, of whom Conrad died after claiming the imperial crown, and Henry forced his father's abdication in 1105, replacing him as Henry V. A daughter, Agnes of Germany, married Frederick I von Staufen, Duke of Swabia. Henry's second marriage (1089-93) was to Eupraxia of Kiev, the daughter of Vsevolod I, Prince of Kiev.