343 Guilty Spark (Earth-2915)

"Last time, you asked me, if it was my choice, would I do it? Having had considerable time to ponder your query, my answer has not changed. There is no choice. We must activate the ring."

- 343 Guilty Spark to John-117

04-343 Guilty Spark, known to the Covenant as "the Oracle", was a forerunner monitor that was originally tasked with maintaining Installation 04. He was often called just "the Monitor" by the UNSC in reference to his title rather than using his name. Guilty Spark played an important role in the modern-day Battle of Installation 04, the heretic uprising within the Covenant, and the events that transpired on the Ark during the Battle of Installation 00.

Source
https://www.halopedia.org/343_Guilty_Spark