the early stories, he is depicted using a gun and metal bat to stop a group of giant assailants and again with a group of average criminals. The Joker, a psychopath who is notorious for using a special toxin called Joker venom that kills and mutilates his victims, remains one of the most prolific and notorious Batman villains created in this time period. By the end of the Joker's second appearance in the series, Batman has, since his debut in 'Detective Comics' killed round nineteen people and one vampire in all, with the Joker having killed only thirteen people, and Robin one. Later, during the Silver Age, this type of supervillain changed from disturbing psychological assaults to the use of amusing gimmicks. Typically, the primary challenges that the Batman faced in this era were derived from villains who were purely evil; however, by the 1970s, the motivations of these characters, including obsessive-compulsion, child abuse, and environmental fanaticism, were being explored more thoroughly. Batman himself also underwent a transformation and became a much less one-dimensional character, struggling with deeply rooted internal conflicts. Although not canonical, Frank Miller's The Dark Knight Returns introduced a significant evolution of the Batman's character in his eponymous series; he became uncompromising and relentless in his struggle to revitalize Gotham. The Batman often exhibited behavior that Gotham's elite labeled as excessively violent, as well as antisocial tendencies. This aspect of the Batman's personality was also toned down considerably in the wake of the DC-wide crossover Infinite Crisis, wherein Batman experienced a nervous breakdown and reconsidered his philosophy and approaches to his relationships. Dennis O'Neil and Neal Adams' work in the early 1970s re-infused the character with the darker tones of the 1940s. O'Neil said his work on the Batman series was "simply to take it back to where it started. I went to the DC library and read some of the early stories. I tried to get a sense of what Kane and Finger were after." Comics historian Les Daniels observed that O'Neil's interpretation of Batman as a vengeful obsessive-compulsive, which he modestly describes as a return to the roots, was actually an act of creative imagination that has influenced every subsequent version of the Dark Knight." Currently, the Batman's attributes and personality are said to have been greatly influenced by the traditional characterization by Dennis O'Neil and Neal Adams' portrayals, although hints of the Miller interpretation