Natalia Alianovna Rmanova, alias Black Widow, is one of the main protagonists from TV series Avengers Assemble and a recurring character from Ultimate Spider-Man.
Agent Natasha Romanoff, alias Black Widow, was a Russian spy and former S.H.I.E.L.D. agent who was recruited to join the Avengers to stop an alien invasion along with Iron Man, Captain America, Thor and Hulk. Over her career she has worked closely with Clint Barton, aka "Hawkeye."
The Avengers Protocol
Black Widow watched on as the Avengers' Quinjet flew towards Red Skull's location, and pursued them in her own vehicle. Once Widow arrived at the destination, she assisted the Avengers in their effort to defeat Red Skull and his Hydra army. After supposedly defeating Red Skull, Black Widow witnessed Red Skull stealing an Iron Man Armor and arc reactor for his own purposes. Black Widow and the Avengers approached Tony, just as he was loosing consciousness.
Black Widow accompanied the Avengers to Avengers Mansion to revive Tony. After Tony Stark recovered, Black Widow and the rest of the Avengers were distraught to learn that Tony had no further use for them. Black Widow left the room to talk to Hawkeye. Soon, the pair were infected by M.O.D.O.K.'s mind-control nanobots, and proceeded to fight each other. After Iron Man was able to rid the team of M.O.D.O.K.'s nanobots, they encountered the Red Skull and defeated him. Red Skull managed to detonate the mansion's reactor, leading the Avengers to scatter. Now without a home, Iron Man welcomed the team to the Avengers Tower. Black Widow and the team were called to action after the Great Wall of China came to life, and flew to their next destination in the Aven-Jet Prime.
Ghost a Chance
The Avengers battle Space Phantoms, extra-dimensional beings who can replicate them right down to cellular level. The creatures replace them one by trapping them in Limbo. But Falcon is able to save the team, and working together, they take down the alien invaders.
The Avengers battle Dracula who had kidnapped Natasha, and turned her into a Vampire. The Avengers travel to Transylvania and confront him at Castle Dracula. He reveals that he was an ally of Captain America during World War II, working together to defeat the invading Hydra forces. He wants the Super-Soldier Serum in Cap's blood which will allow him and his subject the ability to go out in the sunlight. During the fight, he drinks the Hulk's blood, absorbing his powers, and turning the Hulk into a Vampire. However the Hulk gamma cells act like tiny suns and he burns away the infection, which also weakens Dracula. After Dracula is defeated, his minions drag him underground to safety, and Natasha returns to normal.
She was captured along the other heroes by The Collector but was soon freed by She-Hulk and Skaar.
The Contest of Champions
She was chosen to team up with Power Man, Skarr and Spider-Man, by the collector, battling Zzzak, Doctor Octopus and Absorbing Man. She's the only captived hero other than Spider-Man to manage to survive a next round.