William Callisto was a Human Starfleet Officer serving during the 24th century.
He was born in in 2305.
He rose through Starfleet's ranks to Captain in record time, commanding a starship for two tours. Afterward he received a posting to the Office of Strategic Planning.
In 2366 he was appointed as Starfleet's Commander in Chief, the youngest person to hold the ofice at the time.
After the first Borg invasion of the Sol System, he took the following steps to strengthen Starfleet:
- Increased resources to new starship construction
- Doubling the number of Akira and Steamrunner class vessels
- Implementing the Defiant class ASDB Project
- Improving Earth's Defenses
He also took steps to ensure that Starfleet did not lose its dedication to exploration as it made preparations against another Borg invasion and responded to the hostilities of the early 2370s.