Archenemy
From Tardis Wiki, the free Doctor Who reference
The Fourth Doctor noted the Decayed Master to be his "sworn archenemy". (TV: The Deadly Assassin) The Twelfth Doctor later claimed Davros to be his archenemy much to the jealousy of Missy, the female incarnation of the Master. (TV: The Magician's Apprentice)
Amy Pond identified the Daleks as the Eleventh Doctor's archenemies. (TV: Victory of the Daleks)
According to a dissenting account of his Ninth life, the Doctor deemed his upcoming marriage to Emma to be news even his archenemy, the Master, needed to hear. (TV: The Curse of Fatal Death)
