did she act as regent for any monarch?
Yes,  Agnes served as regent on behalf of her young son, Henry IV
Agnes of Poitou
After her husband's death on 5 October 1056, Agnes served as regent on behalf of her young son, Henry IV. 
when did henry iv, holy roman emperor ascend to the throne? 1 April 1084 who was his father? Henry III, Holy Roman Emperor was there any controversy during his crowning? UNANSWERABLE which country did he reign over? Germany, Italy, Burgundy was his father in a conflict with any country? Yes, with Bohemia and Hungary who was this king married to? Agnes of Poitou
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Agnes of Poitou [SEP] Role as regent
After her husband's death on 5 October 1056, Agnes served as regent on behalf of her young son, Henry IV. Henry III had secured the election of his son as King of the Romans on his deathbed. Agnes, aided by Hugh of Cluny and Pope Victor II, also Bishop of Eichstätt, tried to continue her husband's politics and to reinforce the rule of the Salian dynasty. However, despite being related to kings of Italy and Burgundy, she was a controversial leader. In order to forge alliances, she would give away three German duchies: already on Christmas 1056, the Ezzonid scion Conrad III, a nephew of Count palatine Ezzo of Lotharingia, received the princeless Duchy of Carinthia.