^ Photo taken @ Dhoby Ghaut Green 
Danaus chrysippus belongs to the subfamily Danainae, which includes the Monarchs & Tigers, Nymphs and Crows, comprises of about 190 species worldwide.
HortPark, SG 20120402
Monarchs and Tigers belong to the genus Danaus. They are large butterflies, characterised by their orange wings, which have a black apex, and white subapical spots. All butterflies in this subfamily are thought to be toxic or distasteful to avian predators.
HortPark, SG 20130126
Danaus chrysippus is found across the entire African continent, throughout most of Asia south of the Himalayas, on most of the islands of the south Pacific, and across much of Australia.