The First Presidency
The First Presidency is the highest governing body of the Church of Jesus Christ of Latter-Day Saints. It is presided over by the President/Prophet of the Church, with two counselors (assistants) chosen from the Quorum of the Twelve Apostles.
The current First Presidency consists of:
Russell Marion Nelson (President and Prophet)
Dallin Harris Oaks (1st Counselor)
Henry Bennion Eyring (2nd Counselor)
The President of the Church is the most senior living apostle in the Quorum of the Twelve. For example, Russell M. Nelson was ordained in April 1984, making him the most senior apostle. Previously, Thomas S. Monson was the senior most apostle, as he was ordained in 1963.