I think that the Libyan civil war is probably full of memorable moments from both sides of the fighting, but when the dictator Muammar Gaddafi was captured and then subsequently killed it was the biggest moment. It is the most important because it showed the the movement was possible and was going places.
Yes, the capture and killing of Muammar Gaddafi was the most important even on the Libyan civil war timeline, because it symbolized the end of an era. Gaddafi's capture and death did a great deal to give the rebels confidence. It was a sign that things in Libya would change in some way. It became only a matter of how it would change.
The capture and killing of Muammar Gaddafi is the most important event on the Libyan civil war timeline. The turmoil in Lbya caused by Gaddafi is renown and for all of those decades he did not pay any kind of price for the torture and wrongdoings his regime was responsible for. His death finally marked the end of that terrible era.
Muammar Gaddafi had to be removed from power in order for any change in Libya. It is understood as a victory for the revolutionaries, but has yet to be defined as "the victory." The bombing of the US embassy shows that the civil war is still a concern in Libya. However, with Gaddafi gone and no one set to replace him, the stage is set for change.
Though the capture and killing of Gaddafi was important, the most important of the rebellion was when arms were laid down and peace was declared. This gave the country an opportunity to rebuild. It would have been just as effective in the end if Gaddafi had been driven out of the country.