Velenka is a crafty, sly, mako shark that was once part of Goblin's shiver. She can be considered to be the main villain of the whole series until Book 4, since she almost controls all of her leaders with a sign of flattery, except for Hokuu. Later on, she shows much less evil traits and tries to change her ways and help Riptide and the Seazarein against the prehistores. She appears in every book.
Fate: Aquasidor to Barkley
Velenka was fifth in line and advisor to Goblin in his Shiver. She craved power over him and was very persuasive. This helped her get what she wanted. When Rogue Shiver joined Goblin Shiver, Velenka took interest in Gray - noticing his size and strength being odd for a reef shark. She soon suspected he was a Megalodon and took Gray to an ancient cave which concealed a megalodon skeleton to enlighten him. She plotted to kill Goblin and become leader of his Shiver at the Tuna Run - but her plans were thwarted by Rogue Shiver and Takiza, who sucked her and Goblin Shiver into a whirlpool and threw them away with the current.
Battle of Riptide
Velenka was tired of answering to Goblin and organized a plot with Gafin's hitmen (urchins) to get rid of Goblin. She lead him out to a maze of seaweed where he was poisoned by said hitmen. After his death, she assumed the role of leader until Finnivus's armada attacked and destroyed her Shiver. Velenka surrendered and became close to Finnivus. She knew that if she could kill Finnivus, she could become leader of Indi Shiver, the most powerful shiver in the ocean.
Into the Abyss
Velenka soon became one of Finnivus's loyal servants. She answered his every need much to her dislike, but she did it only because she did not want him to doubt her "loyalty". When she grew weary of serving Finnivus, she poisoned his food in the hope that, if/when Finnivus died, she could take over and become the Empress and be the one to order the destruction of Riptide. This did not work, as she was discovered by [[Tydal]] but she tried to place the blame on another shark. To prove her loyalty to him, she obliged when Finnivus ordered her to swim at the very front of the Armada into battle. All her attempts to remove Finnivus and become the Empress of the Big Blue failed, as Finnivus was too powerful and cunning, and much harder to manipulate than Goblin, plus Tydal discovered the poison, which stopped Finnivus from eating it. She survived the final battle and was captured by Gray, Mari, and Barkley when Finnivus was killed and Indi surrendered. She was then imprisoned as the Council decided her fate.
Kingdom of the Deep
After Finnivus was killed, she was placed in prison for a while, but to her surprise, a frilled shark named Hokuu came to her rescue, for which she was grateful. However, she soon realizes that he didn't rescue her for good intentions, and that even she might get killed by him. Velenka soon realizes that this is a shark that she will not be able to manipulate as she did the others, that this shark is probably impossible to kill. As he sets out to kill all shark-kind, she only helplessly watches as more and more sharks die at his fins and swim The Sparkle Blue. After Hokuu gets distracted and ends up in an epic battle with Takiza, she arrives at Gray's destination, and confesses all of her knowledge to Gray and his friends after being put in a trance by Takiza. Takiza comments that she was merely a pawn in Hokuu's giant plan. Afterwards, she was put under Gray's care and command.
Enemy of Oceans
Velenka and Mari were attacked by a group of Mako Finja in the beginning but Snork and Takiza appeared to save them. After Mari dies fighting Hokuu, Velenka attempted to hide her emotions and the fact that she possibly cared for Mari, deep down. She was attacked by a frilled shark during the battle against Hokuu and Grimkahn at the Tuna Run and was, surprisingly, saved by Barkley. She then asks to be a ghostfin as she feels terrible about what she did and she wants to do good now, plus she feels like she owes Barkley.
The Last Emprex
Velenka is promoted to a sub-commander after being eager to learn and to show that she is a good shark inside, plus she defeated Shell and Peen, the top ghostfins. She tries again and again to convince Barkley that she is truly on his side now. She even leads the ghostfins in a revenge attack against Hokuu. After Grimkahn's defeat, Barkley asks her to be his aquasidor, which she delightedly accepts. The book states that maybe someday Velenka would take over and rule the Big Blue like she wanted to before but in a different way. Velenka is now no more an evil shark than Gray himself.
In some illustrations, Velenka is portrayed as a long-fin mako shark and then looks like a short-fin Mako shark. this a recurring error in the series.