Question: What was the name of the mother of Henry II's second cousin, whose death made Henry King of Germany?

Context paragraphs:
Angevin kings of England: The Angevins ("from Anjou") were an English royal house in the 12th and early 13th centuries; its monarchs were Henry II, Richard I and John.  In the 10 years from 1144, two successive counts of Anjou, Geoffrey and his son, the future Henry II, won control of a vast assemblage of lands in western Europe that would last for 80 years and would retrospectively be referred to as the Angevin Empire.  As a political entity this was structurally different from the preceding Norman and subsequent Plantagenet realms.  Geoffrey became Duke of Normandy in 1144 and died in 1151.  In 1152 his heir, Henry, added Aquitaine by virtue of his marriage to Eleanor of Aquitaine.  Henry also inherited the claim of his mother, Empress Matilda, the daughter of King Henry I, to the English throne, to which he succeeded in 1154 following the death of King Stephen.

Henry II of England: Henry II (5 March 1133 – 6 July 1189), also known as Henry Curtmantle (French: "Court-manteau" ), Henry FitzEmpress or Henry Plantagenet, ruled as Count of Anjou, Count of Maine, Duke of Normandy, Duke of Aquitaine, Count of Nantes, King of England and Lord of Ireland; at various times, he also controlled Wales, Scotland and Brittany.  Henry was the son of Geoffrey of Anjou and Matilda, daughter of Henry I of England.  He became actively involved by the age of 14 in his mother's efforts to claim the throne of England, then occupied by Stephen of Blois, and was made Duke of Normandy at 17.  He inherited Anjou in 1151 and shortly afterwards married Eleanor of Aquitaine, whose marriage to Louis VII of France had recently been annulled.  Stephen agreed to a peace treaty after Henry's military expedition to England in 1153, and Henry inherited the kingdom on Stephen's death a year later.

Baron O'Neill: Baron O'Neill, of Shane's Castle in the County of Antrim, is a title in the Peerage of the United Kingdom.  It was created in 1868 for the musical composer The Reverend William O'Neill.  Born William Chichester, he succeeded to the estates of his cousin John Bruce Richard O'Neill, 3rd Viscount O'Neill, in 1855 (on whose death the viscountcy and barony of O'Neill became extinct) and assumed by Royal licence the surname of O'Neill in lieu of Chichester in order to inherit the lands of his cousin, despite not being descended in the male line from an O'Neill.  The Chichesters trace their lineage to the name O'Neill through Mary Chichester, daughter of Henry O'Neill of Shane's Castle.  Lord O'Neill was the patrilineal great-great-great-grandson of John Chichester, younger brother of Arthur Chichester, 2nd Earl of Donegall.  The latter two were both nephews of Arthur Chichester, 1st Earl of Donegall, and grandsons of Edward Chichester, 1st Viscount Chichester (see the Marquess of Donegall for more information).  Lord O'Neill was succeeded by his eldest son, the second Baron.  He sat as a Conservative Member of Parliament for Antrim.

Geoffrey (archbishop of York): Geoffrey (c. 1152 – 12 December 1212) was an illegitimate son of Henry II, King of England, who became bishop-elect of Lincoln and archbishop of York.  The identity of his mother is uncertain, but she may have been named Ykenai.  Geoffrey held several minor clerical offices before becoming Bishop of Lincoln in 1173, though he was not ordained as a priest until 1189.  In 1173–1174, he led a campaign in northern England to help put down a rebellion by his legitimate half-brothers; this campaign led to the capture of William, King of Scots.  By 1182, Pope Lucius III had ordered that Geoffrey either resign Lincoln or be consecrated as bishop; he chose to resign and became Chancellor instead.  He was the only one of Henry II's sons present at the king's death.

Henry II, Holy Roman Emperor: Henry II (German: "Heinrich II" ; Italian: "Enrico II" ) (6 May 973 – 13 July 1024), also known as Saint Henry, Obl.  S. B., was Holy Roman Emperor ("Romanorum Imperator") from 1014 until his death in 1024 and the last member of the Ottonian dynasty of Emperors as he had no children.  The Duke of Bavaria from 995, Henry became King of Germany ("Rex Romanorum") following the sudden death of his second cousin, Emperor Otto III in 1002, was crowned King of Italy ("Rex Italiae") in 1004, and was crowned by the Pope as Emperor in 1014.

Lambert III of Nantes: Lambert III was born in 830 and died in 882.  Lambert was the son of Lambert II of Nantes, at whose death in 851, the administration of the region fell effectively to the Bretons.  After his father's death, Lambert III became a pretender to the County of Nantes seat.  His mother was Tetrata of Lombardy, a daughter of the eldest son of Charlemagne, Pepin of Italy.  Lambert III married Rotrude of Italy, a daughter of Holy Roman Emperor Lothair I.  The Emperor was a first cousin of Lambert's mother, as both were grandchildren of Charlemagne.  Lambert's and Rotrude's only son was Wipert of Nantes.

Viscount Fauconberg: Viscount Fauconberg, of Henknowle in the Bishopric of Durham, was a title in the Peerage of England held by the head of the Belasyse family.  This family descended from Sir Henry Belasyse, High Sheriff of Yorkshire from 1603 to 1604, who was created a Baronet, of Newborough in the County of York, in the Baronetage of England in 1611.  His son, Sir Thomas, the second Baronet, was created Baron Fauconberg, of Yarm in the County of York, in the Peerage of England in 1627.  In 1643 he was further honoured when he was made Viscount Fauconberg, of Henknowle in the Bishopric of Durham, also in the Peerage of England.  He was succeeded by his grandson, Thomas, the second Viscount, the son of the Honourable Henry Belasyse.  Thomas was created Earl Fauconberg in the Peerage of England in 1689.  He was childless and the earldom became extinct on his death in 1700.  He was succeeded in the remaining titles by his nephew and namesake, Thomas, the third Viscount, the son of Sir Rowland Belasyse.  The third Viscount was succeeded by his son, Thomas, the fourth Viscount, who in 1756 was created Earl Fauconberg, of Newborough in the County of York, in the Peerage of Great Britain.  The Earl's son Thomas, the second Earl, had no sons and the earldom became extinct on his death in 1802.  He was succeeded in the remaining titles by his second cousin Rowland Belasyse, the sixth Viscount, the grandson and namesake of Rowland Belasyse, younger brother of the third Viscount.  The sixth Viscount was succeeded by his younger brother, Charles the seventh Viscount, on whose death in 1815 all the titles became extinct.

Otto III, Holy Roman Emperor: Otto III (June/July 980 – 23 January 1002) was Holy Roman Emperor from 996 until his early death in 1002.  A member of the Ottonian dynasty, Otto III was the only son of the Emperor Otto II and his wife Theophanu.

Eleanor, Fair Maid of Brittany: Eleanor Fair Maid of Brittany (c. 1184 – 10 August 1241), also known as Damsel of Brittany, Pearl of Brittany, or Beauty of Brittany, was the eldest daughter of Geoffrey II, Duke of Brittany, the fourth son of King Henry II of England, and Constance, Duchess of Brittany.  After the presumed death in 1203 of her imprisoned younger brother, Arthur, she was heiress to vast lands including England, Anjou, and Aquitaine as well as Brittany, realms where the Salic Law barring the accession of females did not apply.  Her uncle John, King of England was the fifth son of Henry II, and Eleanor inherited Arthur's claim to the throne as child of John's elder brother Geoffrey.  Thus she posed a potential threat to John, and following his death in 1216, equally to her cousin, Henry III of England.  She was imprisoned from 1202, and thus became the longest-imprisoned member of an English royal family.  As a prisoner she was also unable to press her claim to the Duchy of Brittany as her mother's heiress.

England in the High Middle Ages: England in the High Middle Ages includes the history of England between the Norman Conquest in 1066 and the death of King John, considered by some to be the last of the Angevin kings of England, in 1216.  A disputed succession and victory at the Battle of Hastings led to the conquest of England by William of Normandy in 1066.  This linked the crown of England with possessions in France and brought a new aristocracy to the country that dominated landholding, government and the church.  They brought with them the French language and maintained their rule through a system of castles and the introduction of a feudal system of landholding.  By the time of William's death in 1087, England formed the largest part of an Anglo-Norman empire, ruled by nobles with landholdings across England, Normandy and Wales.  William's sons disputed succession to his lands, with William II emerging as ruler of England and much of Normandy.  On his death in 1100 his younger brother claimed the throne as Henry I and defeated his brother Robert to reunite England and Normandy.  Henry was a ruthless yet effective king, but after the death of his only male heir in the White Ship tragedy, he persuaded his barons to recognise his daughter Matilda as heir.  When Henry died in 1135 her cousin Stephen of Blois had himself proclaimed king, leading to a civil war known as The Anarchy.  Eventually Stephen recognised Matilda's son Henry as his heir and when Stephen died in 1154, he succeeded as Henry II.

Supporting paragraphs: Henry II, Holy Roman Emperor Otto III, Holy Roman Emperor
Answer: Theophanu