Green Kit Kat!
After some investigation, it seems it's a limited edition, and available only in Japan.
According to Wikipedia, here's a list of all the flavors available. I had no idea so many were available. Man, where did I live for so many years?
Kit Kat Original — (different taste & texture in different countries)
Kit Kat Fine Dark — UK & Germany variant of Kit Kat Dark Chocolate
Kit Kat Cacao 61% — Japan — newer version of Kit Kat Bitter with 61% cocoa content
Kit Kat Cherry Blossum — Japan —
Kit Kat Cacao 72% — Japan — dark chocolate petits with 72% cocoa content
Kit Kat White Creme — US permanent edition — current version of US Kit Kat White made with vegetable oil based candy coating rather than pure white chocolate
Kit Kat White — Japan
Kit Kat Tea — Japan
Kit Kat Green Tea — Japan
Kit Kat Milky White — Germany variant of Kit Kat White Chocolate
Kit Kat Mint — UK permanent edition, US limited edition — mint flavoured milk chocolate coating
Kit Kat Mint Chocolate — Australia — mint green colour wafers
Kit Kat Apple — Japan
Kit Kat Orange — UK permanent edition, US, Canada, Japan, Malaysia limited edition.
Kit Kat International Recipe — Malaysia, Singapore and selected East Asian countries — The chocolate were made from Ghana cocoa beans thus having the tendencies to melt down very easily when compared to Kit Kat Original.
Kit Kat Café Latte with Hokkaidō Milk — Japan
Kit Kat Kiwifruit — Japan
Kit Kat Strawberry — Japan
Kit Kat Caramac — UK
Kit Kat Chocolate Overload — Australia — Milk Chocolate outside, chocolate creme filling and chocolate wafers
Kit Kat Gold — Japan — petits with fudge like covering and dusted cocoa powder on outside
Kit Kat Noisette (Hazelnut) — Germany
Kit Kat Lite — India — two finger bar with 50% less sugar
Kit Kat Carb Alternatives — US — low carb version with 50% less sugar carbs
Kit Kat Low Carb — UK
Kit Kat Cantaloupe; Japan
Large single finger Chunky bars
KitKat Chunky and KitKat Chunky Peanut Butter, as sold in the UK (September 2006)
Kit Kat Chunky — UK, Canada, everywhere besides US & Japan
Kit Kat Big Kat — Japan & Hershey US version of Chunky
Kit Kat Big Kat Bitter — Japan
Kit Kat Black — Turkey — a dark chocolate chunky
Kit Kat Big Break — UK — extra large Chunky bar
Kit Kat Chunky M.A.X. (Maximum Appetite Xcitement) — Canada — another extra large Chunky bar
Kit Kat Chunky White — limited or permanent edition in many different countries
Kit Kat Cookie Dough — Australia
Kit Kat Chunky Hazelnut Cream — Germany
Kit Kat Honeycomb — Australia
Kit Kat Caramel — US version of Kit Kat Chunky Caramel
Kit Kat Chunky Caramel — Canada, Australia and UK
Kit Kat Editions Golden Caramel — UK — same as Chunky Caramel
Kit Kat Editions Caramel Dream — Germany — another Chunky Caramel
Kit Kat Peanut butter — UK, Canada, Europe, Australia, — Chunky with peanut butter filling
Kit Kat Editions Tiramisu — UK
Kit Kat Extra Crispy — US — Chunky with a six layer wafer
Kit Kat Strawberry; Australia and raises funds for the National Breast Cancer Foundation