His best known role is his 1981 portrayal of "Lord Humungus", the leader of the marauding wasteland gang in Mad Max 2.
In the 1981 post-apocalyptic science fiction action film Mad Max 2 (also known as Mad Max: The Road Warrior), he played the main antagonist "Lord Humungus", the leader of a gang of marauders that besiege a settler compound in the Australian wastelands.
He leads a rag-tag band of biker-berserkers, and he gives speeches to the settlers exhorting them to surrender, while utilizing psychological warfare.
Time magazine's Richard Corliss stated that in Nilsson's portrayal, "malevolence courses through his huge pectorals, [and] pulses visibly under his bald, sutured scalp.
"[2] A year later, he appeared in The Pirate Movie (1982), a musical and comedy film directed by Ken Annakin and starring Christopher Atkins and Kristy McNichol.