Spoilers for "The Flash" revealed that the sister of Leonard, played by Wentworth Miller, will show up to cause some trouble for the gang. Then Cisco's brother might cause some old wounds to be reopened.

According to Access Hollywood, Peyton List of "The Tomorrow People" will play Lisa Snart, Leonard's sister in future episodes.

"While Leonard is cold and calculating, Lisa is a wild child and anxious to prove to her older brother she's got what it takes to be in his criminal gang," according to "The Flash" spoilers. "She is sly, charming, and even a little sadistic. She's also not afraid to use her sexuality to get what she wants, which will put her on a collision course with S.T.A.R. Labs employee and friend of The Flash -- Cisco Ramon (Carlos Valdes)."

It's not clear if her character will follow the same character in the DC Universe as Lisa Snart's alter ego is called The Golden Glider, described as a super villain who started as a figure skater. The Flash killed her boyfriend The Top, which is why she swore to avenge his death and kill the speedster.

"The Flash" spoilers also reveal that another celebrity, Nicholas Gonzales ("Sleepy Hollow"), will also be joining the show as Cisco's brother, said the spoilers from TVLine.

Nicholas Gonzales "will play Cisco's handsome and charming older brother Dante, who is used to being the family favorite," the report said. "Dante is a gifted pianist, but he never reached his potential and secretly resents Cisco's success. When the brothers are thrust into extreme circumstances, Dante must rely on Cisco if they're going to survive."

Both Nicholas Gonzalez and Lisa Snart will first appear on Episode 16 called "Rogue Time."

Watch out for more "The Flash" spoilers which will be revealed as soon as they are available ahead of the airing date on January 20 on The CW Network.