Marius Black

Marius' father was Cygnus Black and his mother is Violetta Bulstrode (Black).  His paternal grandfather was Phineas Nigellus Black and his paternal grandmother is Ursula Flint (Black). He had a brother and two sisters, named Pollux, Cassiopeia and Dorea.  He is the second youngest of the four children.

Here is a link to the TNG Page