Tiger Shark (Todd Arliss) is a supervillain appearing in American comic books published by Marvel Comics. Created by writer Roy Thomas and artist John Buscema, the character first appeared in Prince Namor, the Sub-Mariner #5 (September 1968). Todd Arliss is a recurring antagonist of the antihero Namor. His powers come from both the DNA of Namor and shark DNA. He is also known under the codename Tiger Shark.

Todd Arliss debuted in Prince Namor, the Sub-Mariner #5 (September 1968), created by writer Roy Thomas and artist John Buscema. He appeared in the 1977 Ms. Marvel series. He appeared in the 2018 Avengers series.

Todd Arliss is a selfish Olympic swimmer who, seeking public acclaim, attempts to rescue a drowning man. In the process, Arliss suffers a spinal cord injury when waves push him into a ship. Desperate to regain his swimming ability, Arliss willingly participates in an experiment by scientist Lemuel Dorcas, who splices his DNA with that of hero Namor and a tiger shark. Although successful, the process changed Arliss both physically and mentally, endowing him with razor-sharp teeth and gills and making him savage and predatory.

Becoming a supervillain and calling himself Tiger Shark, Arliss finds and threatens Lady Dorma, demanding to be crowned Lord of Atlantis. Namor, however, deposes Tiger Shark, who is imprisoned in Atlantis. Tiger Shark escapes from Atlantis during a rebellion caused by the artifact the Serpent Crown and encounters Namor once again.

Tiger Shark battles Orka, the minion of Atlantean noble Warlord Krang. The pair cause an undersea avalanche that buries them for several months.

Once free, Tiger Shark discovers he is losing his powers and teams with the villainess Llyra against Namor and his allies Stingray and the Human Torch. Tiger Shark's powers are restored by Llyra, and Tiger Shark accidentally kills Namor's father, Leonard Mackenzie, as the villains retreat. After encountering the Hulk at Niagara Falls, Tiger Shark reunites with Lemuel Dorcas and battles Namor and the hero Spider-Man. On this occasion, Tiger Shark is savagely beaten by Namor and left for dead. Tiger Shark, Dorcas, and Atlantean warlord Attuma seize the island Hydro-Base and again battle Namor, who allied with Doctor Doom. Dorcas is accidentally crushed to death, with Tiger Shark and Attuma being defeated and imprisoned.

Tiger Shark joins the supervillain team the Masters of Evil who battle the Avengers. With the Masters of Evil, Tiger Shark aids villain Egghead in a plan to ruin Hank Pym, but is ultimately defeated by Pym. Tiger Shark joins Baron Helmut Zemo's version of the Masters of Evil and invades Avengers Mansion, escaping when the Avengers retake their headquarters. The character flees with fellow Masters member Whirlwind to California, where both are captured by Avengers West Coast members Tigra and Hellcat.

During the Acts of Vengeance storyline, Tiger Shark battles Wolverine; feigns illness to escape prison, and eventually battles Stingray. Tiger Shark ceases the hostilities to help rescue his sister, who is trapped in a cave-in.