Although the director and writer of "You Who Came From The Stars" could not see anyone other than Jun Ji Hyun playing Hallyu star Chun Song Yi, they sent offers to several male actors.

Kim Soo Hyun was one of those actors. Having enjoyed working with him in the film "The Thieves," Jun Ji Hyun knew he would be perfect for the part of the alien Do Min Joon. She called him up and suggested they do it together. That helped make his decision and the result was some pretty amazing romantic chemistry.

Although audiences already knew the two could create sparks as co-stars, who would have guessed the alien-human romance would be so popular? Apparently these two actors knew that together they had what it took.

The casting of the upcoming drama "Hotel King" also involved a personal request to a potential co-star. Actor Lee Dong Wook called his former co-star Lee Da Hae and asked her if she was willing. The two starred together in the successful drama "My Girl." When he found out she was up for the part, he knew they had to work together again.

"I called Lee Da Hae up myself and asked her if she wanted to do it," said Lee Dong Wook on a recent episode of MBC's "Section TV: Entertainment News."

Will their chemistry sizzle as it did in their last drama? On the entertainment show, he told her that she was just as beautiful as ever.

"It's the first time I have seen her in years," he said. "Even though it has been a while, she still has that same aura."

The drama begins March 29.

When Kim Hee Ae was cast in the upcoming drama "Secret Love Affair," she asked for Yoo Ah In as a co-star.

"I saw him for the first time in the film "Wan Duk" and I was amazed by his talent," she said. I knew that he was going to become a big star. Then he was cast in 'Elegant Lies' as my neighbor. It's not easy for an actor to give up looking attractive but he devoted himself to the role during filming."

Although she did not speak to him much during the making of the film, she was the one that called to convince him to play the part of a genius piano student and her lover in "Secret Love Affair."

"I am glad that Yoo Ah In got to do it," she said. "I don't know who else could have done it other than him."

Despite the age difference, he recently said she was one of the sexiest actresses he knew.

Secret Love Affair starts March 17.

Will the chemistry in "Hotel King" and "Secret Love Affair" be as impressive as that in "You Who Came From The Stars?" Tune in and find out. Let us know what you think.