The Demon's Head AKA Ra's Al Ghul was introduced in 1971 in the pages of Batman #232. The international terrorist often strikes with environmental motivations and is a real bugger thanks to his rejuvenating Lazarus Pits which provide him with unnatural longevity.
Ra's made his masterful onscreen debut during the two-part episode of Batman: The Animated Series, The Demon's Quest in which Batman was courted to be the heir to the Al Ghul Empire and mate to Ra's daughter Talia.
Later in the series; run, Ra's appeared in Showdown, an episode which chronicled the facing off of Ra's Al Ghul and Jonah Hex in the Wild West.
In The Demon Reborn, an episode of the animated Superman series, Ra's sought to tap the strength of Superman after his tried and true Lazarus pits had become ineffective.
Without spoiling too much, Ra's revealed his sick and twisted side in 2000's Out of the Past during the series run of Batman Beyond.
In 2005, Ra's Al Ghul gained mainstream exposure as the prime villain of Batman Begins. In the film, Lazarus Pits were not shown. Instead, Ra's immortality was hinted to be a result of Ra's hiding his true identity.
Although Batman assumed he had rid the world of Ra's Al Ghul early in the film, the supervillain was later revealed as Batman's trainer, Ducard.
In Batman: The Brave and the Bold Ra's Al Ghul first appeared in 2010's Sidekicks Assemble! in which the villain helming a flying island took on the original Teen Titans.
Later in 2010, Ra's played a key role in resurrecting the slain Jason Todd in Batman: Under the Red Hood, a deviation from the continuity punched explanation offered in the original comic book.
In 2011, Ra's Al Ghul was revealed to be a key member of the villainous team, The Light, the primary adversaries of the young super team.
In 2012's The Dark Knight Rises, Ra's Al Ghul will return. Whether Ra's role will be limited to flashbacks or whether the villain somehow survived his showdown with Bat in Batman Begins remains to be seen. Either way, I am betting he won't be the happiest camper.