Wojciech Olbracht Polish prince, youngest son of Sigismund I the Old, died young (1527–1527) Parents Bona Sforza Sigismund I the Old Children Siblings Isabella Jagiellon Sophia Jagiellon, Duchess of Brunswick-Lüneburg Anna Jagiellon Anna Jagiellon Catherine Jagellon Regina Szafraniec Katharina of Poland, Countess of Montfort Hedwig Jagiellon, Electress of Brandenburg Sigismund II Augustus John Jagiellon