It is no secret that in recent years Hollywood has developed an insatiable hunger for producing movie sequels.

In most cases, depending on a film franchise’s potential for success, a sequel eventually leads to the filming of another sequel, therefore consummating the collection better known as the trilogy. As final as these compilations appear to be, there is a growing trend that may soon threaten the life of the modern trilogy. That threat is the fourth film, and it is steadily making appearances in movie franchises thought to be complete.

The issue surrounding the phenomenon of the fourth film is not a general matter of either loving or hating sequels. A fourth installment to a series can be healthy or damaging, depending on the franchise. For instance, the Indiana Jones series starring Harrison Ford is adding another chapter, this time co-starring Shia LeBeouf and “Beowulf” star Ray Winstone. With the talent of old and new, and the high likelihood Steven Spielberg will deliver another captivating and memorable film, the question of necessity remains. Does this movie need to be made? However, sometimes necessity is overrated.

Another Spielberg series, “Jurassic Park,” suffered a devastating blow with its unimpressive third installment, “Jurassic Park 3” (2001). Spielberg didn’t direct it (as he probably should have), and consequently owes his audience a far more appropriate ending to his great science fiction innovation.

However, there are some franchises that might actually be in dire need of revitalization. For instance, “Terminator 3: Rise of the Machines” (2003) was more of an extended chase scene than a worthy conclusion to the classic epic that preceded it. Even some recent releases could benefit from a fourth installment. Despite its blockbuster status and financial prosperity, “Spider-Man 3” was a big disappointment among many fans who felt that director Sam Raimi lost touch of the enchanting essence he captured so well in the first two films.

They will just have to be judged as they come along. Some franchises will make us wish they would have pulled the plug at three, and some may even inspire us to crave a fifth serving. Either way, say goodbye to the finite boundaries of trilogies – because four is on its way to becoming the new three.