For my Suicide Squad, I went with characters born on Earth. My number one requirement was intellect. These four will pull off any job and not even think of the word 'Suicide'!!! They will most likely favor the long game over a quick job.
Immortal Human who has been some the most infamous historical characters including: Julius Ceasar, Genghis Khan, the Pharoah Khafre, Jack The Ripper, Blackbeard and many others. Skilled warrior, tactical planner and master strategist. He is also insanely rich. I picked him over R'as al-Ghul and Ozymandias.
I put her on the team for her shapeshifting ability. She can impersonate anyone which comes in handy for infiltration and covert operations. Mystique is also a cunning strategist in terrorist and commando operations, is adept at martial arts and is an information technology specialist. She is a talented actress and is fluent in over fourteen languages.
This character is from the Harry Dresden series by Jim Butcher. He is also a skilled leader which may put him into conflict with Vandal Savage. The oldest and most powerful of the Denarians (possessor of one of the thirty coins used to pay off Judas Iscariot for betraying Jesus Christ) , he is possessed by the fallen angel Anduriel, one of Lucifer's captains. Anduriel typically manifests as Nicodemus's own shadow moving independently of him. This shadow form can also manifest solidly to attack, hurl or break objects, or even act as wings to allow Nicodemus to fly at speeds matching a freight train. Perhaps his most powerful ability is "to hear anything uttered within reach of any living being's shadow, and sometimes to look out from it and see." Nicodemus possesses the rope Judas Iscariot used to hang himself with after the crucifixion. While wearing the slender rope as a tie, Nicodemus is invulnerable to attack even by Denarian standards, utterly immune to all methods of death except strangulation with the rope itself. He possesses super human strength and a great deal of magical knowledge.
I loved the traditional Prof. James Moriarty, played by Jared Harris, in the Sherlock Holmes movies. He was spot on for the literary character. I also loved the twist with Moriarty in the TV series Elemenatry. But, Jim Moriarty in the BBC series Sherlock is by far the one I would want in my Suicide Squad. He is a master manipulator and infiltrator. He has no super powers. His motivation is not money or power, but to see if he can pull off his plans. Given the talents of his other teammates, I can see him getting jazzed over any operation! He may be the most fragile on the team, but his talents have protected him quite nicely.
Kang The Conquerer
Morgan le Fay (Marvel comics)