This is about Sabbat Cardinals. For information on Cult Cardinals, see Cult of the Emperor.
Cardinal is a title used in the Sabbat hierarchy. They function as the executive management of the Sabbat, subordinate only to the Regent (currently Mordred). There is no direct parallel rank to Cardinal among the Camarilla; in terms of sect status and influence, the closest would be an archon or even a justicar.
Cardinals, advised by Prisci, are responsible for large Regions, often one or more entire star systems, consisting of several archdioceses administered by Archbishops. In addition to planning and delegating all Sabbat activity with their Region, Cardinals advise the Regent, have the authority to make or break alliances and declare enemies, to promote or demote Sabbat members of lower rank, and handle all disputes that couldn't be resolved by the Archbishops or Bishops. Cardinals seldom answer to the Regent or the Prisci unless their activities have a detrimental effect on the Sabbat as a whole.
All Cardinals are elders at least a few centuries old (the youngest dating from around the Elizabethan era). As such, Cardinals contain vast personal power in the form of their generation, mastery of Disciplines, personal wealth, and significant control over the mortal world.