AFTER a quiet spell on the acting front, Katie Holmes is set to make an appearance on the up-coming Halloween episode of How I Met Your Mother - as a promiscuous Jack-O-Lantern! The 32-year-old actress will play the character of a woman who Josh Radnor's character, Ted Mosby lost touch with after a Halloween party in freshman year and now resurfaces as a potential love interest, New York Magazine's Vulture blog reports. Co-creator Craig Thomas told the site, after finally casting a role "literally six seasons in the making," he is thrilled with his pick. "Katie is a lovely and talented actress," he says of the star, "which is why we've saved for her perhaps the most classily named character in our show's history."