Creation and Sacrifice
Creation Through Sacrifice
The theme of creation through sacrifice runs core throughout the movie. There are many sequences that suggest that the Engineers view the creation of life through sacrifice and death as the natural order, suggesting that anything that runs counter to it violates this ideology (see: Creation Gone Wrong).
Here are the sequences that drive forward the themes of creation and sacrifice:
The Opening
According to director Ridley Scott, the opening sequence, which may or may not take place on Earth, shows one of the Engineers sacrificing himself; essentially donating his life to a higher, undisclosed purpose.
The black substance the Engineer drinks is the catalyst for transformation and creation of life itself. The movie itself does not spell out why the Engineer sacrificed himself, but Scott's mention of the similarities to human sacrifice suggests that the goal was to provide the "spark of life" and set into motion the chain of evolution -- a process of creation of new life forms through sacrifice/death of what comes before it.
Prometheus
In classic Greek mythology, Prometheus, son of the Titan Iapetus and god of forethought and crafty counsel, was entrusted (alongside Athena) with the moulding of mankind out of mud and wind. He is said to have given to men something of all the qualities of other animals.
He falls from grace when he betrays the gods, first by stealing the sacrificial meat from their feast and giving it to man, and then by stealing fire from heaven and delivering it to the mortals. Zeus punishes both mankind and Prometheus. He creates Pandora to deliver misfortune to men and has Prometheus seized and bound to a pillar where an eagle sent by Zeus would devour his liver for all eternity. Prometheus is often described as a heroic sufferer, who through his sacrifice, gave fire (life) to humans.
The myth the movie takes its name from is not just referenced in theme, but also more directly through the mural shown in the chamber with the stone head effigy and black substance containers inside the Engineers' ship. The image clearly depicts Prometheus with his side torn open.
Peter Weyland himself references the myth, quoting T. E. Lawrence:
Lawrence summarizes the realization that in order to achieve something, you have to make a sacrifice.
BIRTH OF THE CREATURE
The sequences detailing both Shaw and the surviving Engineer "giving birth" to the proto-alien creatures both tie in with the image of Prometheus, the life giver, with his side torn open. Shaw uses the surgery chamber to open up her own insides and extract the creature, while the Engineer battles the rapidly grown-up creature fearlessly, and -- as it seems unwillingly -- gives birth through his own death.
Salvation through Sacrifice
The end of the movie picks up the sacrifice motif once again. The crew of the Promotheus stops the destruction of mankind by sacrificing their lives and crashing the ship into the Engineers' craft.