Sounds like you forgot to mention which game you are talking about. Perhaps you could tell us?

IWD2.

Bump...

Why can't you? Just change it. It really is that simple. There are no set rules, just use your imagination.

-Grab some dice (or random.com), and roll to find out each character's race.

-Roll a die to pick one of Cleric/Druid. Roll a die to pick one of Bard/Wizard/Sorcerer. Roll a die to pick one of Fighter/Paladin/Barbarian. For each remaining character slot, roll a die to pick which class (from the full list of classes) goes in that slot.

-Combine (1) and (2) above, though you can assign which races and classes are pair together. Or just randomly pair them together.

You'll get something that should be able to complete the game, but will be different from your usual fare.

Try doing a themed party.

Snow White and the Seven (err… Five…) Dwarves

Snow White: Female Human Bard
Grumpy: Male Dwarf Fighter. Low charisma.
Dopey: Male Dwarf Fighter. Low intelligence and wisdom.
Happy: Male Dwarf Bard.
Doc: Male Dwarf Cleric.
Bashful: Male Dwarf Thief.

The Avengers

Cap America: Male Human Fighter. Always uses the best shield available and specializes in sword and shield combat style.
Iron Man: Male Fighter/Mage. Wears full plate and uses wands.
Hulk: Male Half-Orc Barbarian.
Black Widow: Female Human Thief (Assassin kit).
Hawkeye: Male Human Ranger (Archer kit).
Vision: Male Human Sorcerer.

Make a group of all bards and name them after your favorite musicians.

Obviously, Lord of the Rings... but that's very cliche.