The former foreign secretary announced this morning that he was quitting as MP for South Shields.
The news comes two and a half years after the bruising Labour leadership battle which pitted the Miliband brothers against each other and was won by a whisker by Ed.
Labour leader Ed Miliband said today that British politics will be "a poorer place" without his brother David.
As he's set to join the International Rescue Committee humanitarian organisation in New York, Twitter has been inundated with Thunderbirds jokes and pictures.
As well as our own Photoshopping efforts above, here are some other reactions (and more impressive Photoshopping):
@RAPP_UK David Miliband turns his back on politics to join the International Rescue gang on Tracy Island. THUNDERBIRDS ARE GO!
@BenjoMess Am I the only person in the world concerned about David Miliband becoming the new head of Thunderbirds? Guys?