Venom has had a wide variety of hosts over the years, and though they range from heroic to villainous, one host lost it all to the alien symbiote. Not in the sense that they were defeated while fighting as one with the symbiote... but that the symbiote itself decided to end their partnership.
During 2003's Marvel Knights: spider-Man #8 citizens of New York were being attacked, each one with a rare form of cancer, and their kidneys being punctured. After Spider-Man encountered the Venom symbiote attacking one such person, he realized that the symbiote is separated from Eddie, and attacking these people on its own. After Spider-Man tracked down Eddie Brock and attempted to get him and the symbiote to surrender, Eddie reveals that he has cancer, and that the symbiote has been feasting off of Brock's cancer and keeping him alive. Soon afterwards, Eddie decides to sell the symbiote to an auction house full of super-villains and criminals, with the proceeds of the auction going to charity. Though Eddie believed this act of ridding himself of the suit, and donating the money to a worthy cause, would redeem him, it only damned another, weaker host.
The winning bid was placed by reputable mafia boss Don Fortunato, who wished to give the suit to his youngest son, Angelo. Angelo, in the Don's eyes, was something of a failure, and hoped that the symbiote would help his son make something of himself, with Angelo himself hoping for power all his own. Eddie reveals to Angelo that the symbiote knows Spider-Man's true identity, Peter Parker, and that the suit would be more then willing to tell him "if he asked nicely." This led Angelo, now the new Venom, to attack Peter while he attended a High School reunion, and injure some of his classmates, even killing one in the process. Peter is aware that this new Venom is Angelo and, after changing into his Spider-Man costume, proceeded to fight him.
Though Angelo gained the upper hand early in the fight, having learned many of the symbiote's tricks very quickly, Spider-Man decided to stop pulling his punches and quickly overwhelmed the young Fortunato. When Angelo tried to flee the fight, the symbiote berated him for running away, even telling him that his father would be disappointed in him. Angelo continued to flee, and as he attempted to jump from one rooftop to another, the symbiote removed itself halfway through, and told him that he "needs a little more Venom." While the suit fled the scene, Angelo fell and, despite Spider-Man's attempts to save him, he died immediately upon hitting the ground.
Angelo Fortunato was something of a sad caracter, raised by a criminal father who had high expectations of him, he never felt that being himself would lead anywhere. The venom symbiote was an opportunity for him to reinvent himself and, given the Venom symbiote's history of being both good and evil, he would have had very little resistance from the symbiote regardless of what path he chose. However, Angelo chose the easy way, harming innocents in an attempt to fight a hero who, time and time again over the years, defeated Venom. Angelo was also afraid of loss, afraid to get beaten, and ultimately couldn't finish a fight that he started.
Had Angelo lived past this point, he could have been reintroduced as a host of another symbiote, perhaps humbled from his loss and looking for redemption. As it stands however, Angelo is a footnote in the long and complex history of the Lethal Protector, Venom.