Lego Series 1. Released in 2010. Part number #8683. 

Each minifigure was sold individually in opaque polybags and came with a selection of accessories, a special display stand, and a paper checklist. The packaging was intended to make the minifigure a person bought random, however, it was quickly noticed that the barcodes on the back could identify the contents. The barcode was removed from Series 3 onwards.

LEGO initially underestimated the demand that these minifigures would create, particularly in America. While stocks were often plentiful in European stores, the minifigures were in extremely limited supply in other territories and shops would often sell out their small allotments within a day. Later series' redressed this issue, but Series 1 remains a highly sought-after item because of these problems.