They're the most famous duo to play the Griswold children, Audrey and Rusty, so why didn't Juliette Lewis and Johnny Galecki return beyond National Lampoon's Christmas Vacation? Of the original National Lampoon's Vacation movies, the third outing Christmas Vacation has emerged as the favorite. Of course, the holiday setting gives audiences an excuse to revisit it every Christmas, but it's also just the funniest and warmest. The sequel continued the unspoken tradition of recasting Audrey and Rusty each time, with Juliette Lewis and Johnny Galecki inheriting the roles from Dana Hill and Jason Lively.

Christmas Vacation found Lewis and Galecki at the beginning of their acting careers, with the duo soon finding fame elsewhere. Lewis went on to roles in 1991's Cape Fear remake, the controversial Natural Born Killers, and more recently, the acclaimed thriller Yellowjackets. Galecki went to roles in two of the biggest sitcoms of the last few...