From Wikipedia:

Peter IV Rareș (Romanian: Petru Rareș pronounced [%CB%88petru ˈrareʃ] or Petru al IV-lea Rareș; ca. 1487 – 3 September 1546) was twice voievod of Moldavia: 20 January 1527 to 18 September 1538 and 19 February 1541 to 3 September 1546. He was an illegitimate child born (probably at Hârlău) to Ștefan cel Mare. His mother was Maria Răreșoaia of Hârlău, whose existence is not historically documented but who is said to have been the wife of a wealthy boyar fish-merchant nicknamed Rareș "rare-haired" (i.e., bald). Rareș thus was not Petru’s actual name but a nickname of his mother’s husband.

Petru exhibited many of his father's qualities: ambition, daring, bravery, piety, artistic taste. However, he was marked by inconstancy and a lack of political instincts.

Children

With Maria, killed 28 June 1529:

1. Bogdan (d. 3 September 1534)
2. Ana (d. 1545), wife of Wallachian prince Vlad VI Înecatul
3. Maria (d. 1614) wife of boyar Radu Balică, then of Ioan Movilă of Hudeşti, whom she bore the princes of Wallachia and of Moldavia, respectively Ieremia Movilă and Simion I Movilă
4. Chiajna (ca. 1525–1588, Constantinople), wife of Wallachian prince Mircea V Ciobanul

With Serbian princess Jelena Branković (ca. 1502–1552 (strangled)), daughter of despot Jovan Branković, married to Rareş in 1530:

1. Ilie II Rareş, (b. 1531), prince of Moldavia
2. Ştefan VI Rareş (b. 1532), prince of Moldavia
3. Constantin (1542 – 26 March 1554, Constantinople)
4. Ruxandra (d. 1570), wife of Moldavian prince Alexandru IV Lăpuşneanu

With the Saxon Ecatarina of Kronstadt (illegitimate issue):

1. Iancu Sasul, prince of Moldavia

With an unknown woman (illegitimate issue):

1. Bogdan Constantin (d. 1573), pretender to the Moldavian throne

http://pl.wikipedia.org/wiki/Piotr_Raresz