The Mages Guild appear in The Elder Scrolls Online. One way to increase reputation with this faction is to search Tamriel for hidden Lore books. Sufficient reputation increase will unlock additional skills, perks and abilities.
The Fighters Guild is a joinable faction in this game. One way to increase reputation in this guild is to destroy Dark Anchors of Molag Bal. With enough reputation, new skills and abilities will be unlocked.
The Undaunted is a guild involved in dungeons, and has its own unique skill line.
The Thieves Guild is dedicated to the gathering and training of those who are stealthy and shadowy in nature. Although criminal by its very definition, for untold years, local authorities in places throughout Tamriel have tolerated the existence of the guild for its role as "Crime Regulator".
The Dark Brotherhood is a guild of professional assassins which historically possessed considerable influence and power but has recently fallen on considerably harder times.