Helena of Znojmo (Czech: Helena Znojemská; Polish: Helena znojemska; c. 1141–1202/06), was a Bohemian princess, a member of the Přemyslid dynasty. She was the daughter of Duke Conrad II of Znojmo and his Serbian wife Maria of Rascia (daughter of Uroš I). Helena was probably named after her maternal aunt, Queen Helena of Hungary, wife of King Béla II.
Born as princess of the Znojmo Appanage (named after its centre, the town of Znojmo in southern Moravia), later became thanks to marriage Duchess of Masovia (1186–1194) and Duchess-regent of Cracow (Kraków), Sandomierz and Masovia on behalf of her minor son during 1194–1199/1200.
Helen married the Casimir II the Just, youngest son of Bolesław III Wrymouth, probably shortly after his return from captivity.
When on 1 May 1194 Helen's husband died, presumably as a result of a heart attack, he left her with their two minor sons on whose behalf she took regency of Lesser Poland and Masovia with blessings from Bishop of Kraków Fulko and Kraków Voivode.
Helen's regency was not an easy one, because other princes threatened the minors., their own uncle Mieszko III the Old was after Kraków. Bloody stocks, which were the culminating moment of the Battle of Mozgawa between Helen and Mieszko, it lasted until 1198 when they reached an agreement with Duke of Greater Poland. Mieszko would take Kraków, in return for which he gave Helen and her sons Kuyavia. Independent authority over the inheritance was taken on by Leszek the White who took over in 1199 or 1200. The great political and intelligent Helen testied words written in the chronicle of Vincent Kadlubek, who certainly knew the princess in person. According to him Helen was "a woman with greater wisdom than usually women have".
Helen of Znojmo died between 1202 and 1206, probably on April 2.
Helen and Casimir had the following children:
- A daughter [Maria, Anastasia?] (1162/67 – 1194), married in November 1178 to Prince Vsevolod IV of Kiev.
- Casimir (ca. 1162 – 2 February or 1 March 1167), named after his father.
- Bolesław (ca. 1168/71 – 16 April 1182/83), probably named after his paternal grandfather Bolesław III Wrymouth, although is possible that in fact was named in honour to his uncle Bolesław IV the Curly. He died accidentally, after falling from a tree. He was probably buried at Wawel Cathedral.
- Odon (1169/84 - died in infancy). He was probably named after either Odon of Poznań or Saint Odo of Cluny.
- Adelaide (ca. 1177/84 – 8 December 1211), foundress of the convent of St. Jakob in Sandomierz.
- Leszek I the White (ca. 1184/85 – 24 November 1227).
- Konrad (ca. 1187/88 – 31 August 1247).
- There is however a very unlikely possibility, but which can not be completely ruled out that Helen was the second wife of Casimir the Just. But no mention about this in the sources, hence this hypothesis is merely a logical structure, which even more reduces its credibility. Cf. Jasiński K., op. cit., p. 267
- K. Jasiński: Rodowód Piastów małopolskich i kujawskich, Poznań–Wrocław 2001, p. 14.
- K. Jasiński: Rodowód Piastów małopolskich i kujawskich, Poznań–Wrocław 2001, p. 15.
- K. Jasiński: Rodowód Piastów małopolskich i kujawskich, Poznań–Wrocław 2001, p. 16.
- K. Jasiński: Rodowód Piastów małopolskich i kujawskich, p. 247.
- S. Pelczar: Władysław Odonic. Książę wielkopolski, wygnaniec i protektor Kościoła (ok. 1193-1239), Editorial Avalon, Kraków 2013, pp. 62–64.
- K. Jasiński: Rodowód Piastów małopolskich i kujawskich, pp. 23-25.
- K. Jasiński: Rodowód Piastów małopolskich i kujawskich, pp. 30-32.