Katarzyna Tomicka (c.1517–1551) was a Polish noblewoman,[1] known as the sister-in-law and opponent of her sister-in-law queen Barbara Radziwiłł.

Katarzyna was born in Iwno, the third daughter of podkomorzy of Kalisz, Jan Tomicki h. Łodzia and sister-aunt of the Court Marshal and Bishop of Kraków, Piotr Tomicki h. Łodzia.

Her sons initiated the so-called "Calvinist lineage" of the Radziwiłł family.

Katarzyna married Mikołaj "Rudy" Radziwiłł around 1542 and had three children:

This biography of a Polish noble is a stub.