#2 Former WWE Tag Team Champions The Shield
The Shield is a WWE faction that created world champions out of all its members. While Jon Moxley currently plies his trade in AEW, Reigns is the reigning Universal Champion and Rollins is an important member of the roster.
The Shield never had an official leader. Early on, fans contemplated Ambrose as the top dog, due to his aggression. However, Reigns was then seen as the cool-headed leader of the group. However, they never mentioned leadership duties in a promo or interview.
The trio went on to become one of the most popular factions of recent times, successful as both heels and faces.
#1 Former WWE Raw Tag Team Champions The New Day
The New Day is an incredibly rare unit of the company, as it is impossible to mark them as a tag team or a faction.
Nothing has been able to break the bond between Woods, Kingston and Big E, and while the current WWE Champion is on the roster of a different brand, he still appears to help his stablemates.
The company is often criticized for their inclination towards breaking teams without reason. The New Day is the biggest exception to a rule that even The Shield couldn't escape.
The team doesn't have an official leader, although it started with Xavier Woods as a manager trying to unite the constantly defeated Kofi Kingston and Big E.