Rick Prime (ex-boyfriend)

Skills and Powers
Superhuman intelligence: Even among Ricks, he is considered one of the most brilliant. He creates technologies that surpass those of almost any other Rick.
Advanced technology: Modified portal gun, armor, weapons that can destroy planets, mind control devices, etc.
Combat: He is an extremely competent fighter, capable of facing multiple Ricks and Mortys at the same time.
Dimensional manipulation: He can travel between universes with ease and has deep knowledge of the structure of the multiverse. Relative immortality: Like many Ricks, he has found ways to avoid permanent death (clones, transferred consciousnesses, etc.).

Rick Prime is the first Rick to discover interdimensional travel and portal technology. Instead of using it to explore or help others, he chose to conquer and destroy realities.
He formed the Citadel of Ricks originally as a way to dominate all other Ricks, but it eventually turned against his own creation. He is responsible for the "Ricketest Rick" and is considered by many to be the most dangerous Rick to have ever existed.
In seasons 5 and especially 6, his role becomes incredibly important. He reveals that he was the one who killed Rick C-137's family, which explains the protagonist's deep depression and alcoholism. His conflict with Rick C-137 is personal and philosophical: both are supreme geniuses, but one chose love (though he denies it) and the other chose absolute power and destruction.

Rick Prime represents the purest and most extreme version of Rick Sanchez's nihilism, intelligence, and evil. Unlike most Ricks (who are chaotic geniuses but with some kind of attachment, however minimal), Rick Prime is:
Extremely arrogant and narcissistic.
Sadistic and cruel without limits.
Deeply bored with existence, which leads him to destroy entire universes just for fun or to demonstrate his superiority.
Master manipulator who sees others (even other Ricks) as insects or toys.
He completely lacks empathy. He killed Rick C-137's (the protagonist Rick's) wife and daughter simply because Rick refused to join him in his "cause."
It's basically what Rick C-137 could have been if he had never experienced the loss of his family and hadn't developed his obsession with protecting Morty.

Rick Prime has the classic look of a Rick Sanchez:
Long, messy, bluish-gray hair.
Dirty and worn white lab coat. A little darker and grayish.
Wrinkled and paler skin, bloodshot eyes, and a hunched but threatening posture.
His design is virtually identical to the rest of the Ricks, but his facial expression conveys a higher level of sadism, arrogance, and madness.