Turtle

The Turtle is the opposite of the Flash: as a conduit of the Still Force, he is super-slow.

The Turtle grew up in an abusive household, however this didn't stop his intellect from shining. The boy graduated from school far earlier then any of his classmates and quickly became a leading scientist. The scientist spent most of his time with his wife and children, slowing down his scientific advancements and allowing his peers to surpass him. Growing jealous of his peers, the scientist began experimenting with a mysterious energy force that he believed kept the universe moving forward. In his jealously the scientist rushed the experiments, hoping to prove his genius again. His experiment quickly meandered out of control and the scientist was caught in an explosion.

The explosion accelerated the scientist's age, giving him the body of a feeble old man. Furthermore his movement was slowed and he stopped aging physically or mentally. His family helped him through the recovery process and soon enough he could once again move like his old self, however he still kept the appearance of an old man. He experimented with this energy force for decades, discovering he could negate any form of motion, including the progression of life. Eventually he became disillusioned with human life as he knew that he would outlive everyone he loved, this led him to kill his family with his powers as he saw them as a needless distraction from his work. Eventually he began going by the name "Turtle", most likely because of the motion negating powers he now possessed.