Movie sequels are typically born of the second-most base of instincts, greed, which doesn't speak well of their artistic intentions.

Still, sequels have the benefit of established characters. Framed properly, they can be a gripping second act in a larger narrative while also serving as a strong isolated narrative.

"Iron Man 2" opened Friday, two years after the original pulled in more than $300 million at the box office.

The back story for Tony Stark has been established. Now will the franchise move it forward? Or try to cover shortcomings with explosions?

Here are a few second movies that did it right, some of them better than their predecessors (in no specific order).

"The Empire Strikes Back" — 1980 sequel to "Star Wars."

Upping the ante: Paternity revelation, Boba Fett!

Result: Quibblers would point out this is Volume 5, but let us not discuss the prequels. Briskly paced and insanely varied in its settings, this one admirably lacked the tidy resolutions of its predecessor and its successor.

"The Dark Knight" — 2008 sequel to "Batman Begins."

Upping the ante: Flipped 18-wheeler, best villain ever.

Result: A little long-winded but nevertheless an unflinchingly bleak movie for our grim times. Another Batman project is reportedly in development. Its creators have their work cut out for them.

"Spider-Man 2" — 2004 sequel to "Spider-Man."

Upping the ante: Subway fight; tentacled villain.

Result: A companion piece to the original when a continuation would've sufficed. Alfred Molina's Doc Ock's final moments are heartbreaking as he's revealed not as a monster but a man possessed by an outside force.

"The Godfather: Part II" — 1974 sequel to "The Godfather."

Upping the ante: Robert De Niro, more Al Pacino, fratricide (by proxy).

Result: Clever use of prequel in the sequel gave this masterpiece two narratives to help it achieve the most stylishly filmed massive body count in movie history.

"Before Sunset" — 2004 sequel to "Before Sunrise."

Upping the ante: Even more conversation!

Result: Another compelling gabfest from Richard Linklater, Ethan Hawke and Julie Delpy. The ending is left open, but Hawke's lupine grin suggests his character is about to make a very bad decision.

"Evil Dead 2" — 1987 sequel to "Evil Dead."

Upping the ante: Flying eyeball, "Workshed!", chain saw.

Result: Director Sam Raimi had proved he could do fright films, but "Evil Dead 2" rejiggered the genre to make room for a wicked sense of humor and some playful camera work.

"The Road Warrior" — 1981 sequel to "Mad Max."

Upping the ante: Long silences, dog killed by crossbow.

Result: George Miller's dystopia was shot with such certainty that I still can't really envision any horrible future that doesn't involve gas shortages and roving bands of evil marauders in the desert.

Technicalities "Harry Potter and the Prisoner of Azkaban" was a moody detour in the series, but it was a third installment. "Aliens" was a good action film, but its predecessor was a contemplative musing about what lurks inside us.