The Sith that was given the honor of attacking the Jedi Temple exactly after the announcement of Order 66 was Darth Vader and he made full use of that golden opportunity. Every Jedi within the Temple was killed and one can only speculate as to just how many were killed by the 501st Legion and how many were killed by Anakin himself (possibly hundreds).

During his time as Darth Vader, the powerful Force-user continued to hunt down Jedi, devoting himself to the Order’s extinction until he became aware of his son’s existence.