Conrad II of Italy, also known as Conrad (III) (12 February 1074 – 27 July 1101), was the Duke of Lower Lorraine (1076–1087), King of Germany (1087–1098) and King of Italy (1093–1098). He was the second son of Holy Roman Emperor Henry IV and Bertha of Savoy, and their eldest son to reach adulthood, his older brother Henry having been born and died in the same month of August 1071. Conrad's rule in Lorraine and Germany was nominal. He spent most of his life in Italy and there he was king in fact as well as in name.

Conrad was born on 12 February 1074 at Hersfeld Abbey while his father was fighting against the Saxon rebellion. He was baptised in the abbey three days later. After Henry's victory against the Saxons, he arranged for an assembly at Goslar on Christmas Day 1075 to swear an oath recognising Conrad as his successor. After the death of Duke Godfrey IV of Lower Lorraine on 22 February 1076, Henry refused to appoint the late duke's own choice of successor, his nephew, Godfrey of Bouillon, and instead named his two-year-old son Duke of Lower Lorraine. He did appoint Albert III of Namur, the deceased duke's brother-in-law, as his son's vice-duke (vicedux) to perform the daily functions of government. He also allowed the march of Antwerp to pass to Godfrey of Bouillon. The total absence of Conrad from his duchy caused or abetted the decline of ducal authority in it. In 1082, while Conrad was in Italy, the peace of God was introduced into the diocese of Liège.

Conrad passed Christmas 1076 at Besançon with his parents. Early the next year (1077) he accompanied his father across the Alps on the way to Canossa, because there was nobody in Germany to which Henry could entrust his son. Conrad subscribed to his first royal charter in 1079. When Henry returned to Germany, Conrad remained in Italy to act as a pledge to the imperialist party there. He was placed in the care of Archbishop Tedald of Milan and Bishop Denis of Piacenza, both excommunicated prelates and opponents of Pope Gregory VII. In October 1080, Conrad was present in the camp when a force from northern Italy defeated the troops of Marchioness Matilda of Tuscany near Mantua.

In December 1080, the Saxon lords who had supported the kingship of the late Rudolf of Swabia against Henry gathered "to discuss the state of their kingdom [Saxony]" in Bruno of Merseburg's words. Henry sent envoys to the Saxons asking them to accept his son Conrad as their king, and in exchange he promised never to enter Saxony. (Conrad was apparently back in Germany.) Otto of Northeim, speaking for the Saxons, "desired neither the son nor the father" since he had "often seen a bad calf begotten by a bad ox."

In 1081, Henry entered Italy, where he endeavoured to wed his son to a daughter of Robert Guiscard, Duke of Apulia. He offered Robert the march of Fermo as well, but no marriage could be agreed to since the duke refused to do homage for Apulia. Again Henry left Conrad in Italy (July 1081), this time in the care of the lay princes "to watch over the province for him", according to the Annales Brunwilarenses and Annales Patherbrunnenses.

In 1087, Conrad returned to Germany. On 30 May, he was crowned king in Aachen by Archbishop Sigewin of Cologne. The ceremony was attended by Albert of Namur, Godfrey of Bouillon and Duke Magnus of Saxony, according to the Annales Weissenburgenses. The last reference to Conrad as duke of Lower Lotharingia (dux Lothariorum) comes from a charter issued at Aachen shortly before his coronation, after which Henry appointed Godfrey of Bouillon duke in his place. By January 1088 Conrad had returned to Italy, with Bishop Ogerius of Ivrea as his chancellor and advisor. Shortly after his return to Italy, his mother died. The passing of Bertha perhaps provoked the rupture between Conrad and his father.

In Italy, Conrad was unsuccessful in resisting Matilda of Tuscany until his father came down in the spring of 1090. In 1091 he was at his father's side, as his "most beloved son". On 19 December 1091 Conrad's grandmother, the Margravine Adelaide of Turin, died. She had named her ten-year-old great-grandson, Peter, as her heir following the death of Peter's father, Count Frederick of Montbéliard on 29 June 1091. Henry, however, declared Conrad the rightful heir and placed him in charge of the march. The southern counties meanwhile were seized by Boniface I of Vasto and Henry granted the county of Asti to the bishop elect Oddo. Throughout 1092 Conrad was campaigning in the march of Turin to establish imperial control.

In 1093, with the support of Matilda and her husband, Welf V, along with the Patarene-minded cities of northern Italy (Cremona, Lodi, Milan and Piacenza), Conrad rebelled against his father. According to Ekkehard of Aura, he was instigated to revolt by "one of his father's ministeriales, who was likewise named Conrad". This was perhaps the same person as the Count Conrad sent by the young king as an envoy to King Roger II of Sicily, according to Geoffrey Malaterra. Ekkehard otherwise gives positive account of Conrad's motivation, describing him as "a thoroughly catholic man, most devoted to the apostolic see, inclining to religion rather than government or war ... well enough furnished with courage and boldness [yet] preferr[ing] to occupy his time with reading rather than with sports". Other sources favorable to Conrad include the Annales sancti Disibodi and the Casus monasterii Petrishusensis. Among sources unfavorable to him are the Annales Augustani and Henry IV's anonymous biography, the Vita Heinrici IV, which describes Conrad as a pawn in hands of Matilda of Tuscany. Bernold of St Blasien records that Henry was so abject after Conrad's rebellion that he attempted suicide, but this may be a hyperbole allusive to the suicide of the biblical King Saul.