Heller Zemo is the third Baron in the Zemo lineage. Heller befriended his descendant Helmut Zemo after the latter was thrown back in time when one of the moonstones was destroyed.
Helmut urged Heller to assassinate Heller's father, Hademar, and prevent him from ruling the family Barony after the death of Heller's grandfather, Harbin Zemo. Heller was 12 years old when he had his father murdered by his own guards at his inauguration.
According to Helmut, of the 13 Barons in the line, Heller was the most progressive.