Skin Pack 3 - Minecraft Guide - IGN

Skin Pack 3 contains 45 skins for Minecraft: Xbox 360 edition including characters from Left 4 Dead 2, Portal 2, and Half Life. It was released on October 17

Skin Pack 3 - Minecraft Guide - IGN

Festive Skin Pack - Minecraft Guide - IGN

Skin Pack 3 - Minecraft Guide - IGN

Not sure what other skins will be available in skin pack 4 but the borderlands characters were confirmed on borderlands Facebook page (Second picture in comments) : r/Minecraft360

Minecraft (Xbox 360) - SKIN PACK 3 - Overview and Impressions!

New Borderlands Skins Headed to Minecraft Xbox 360 Edition - IGN

Skin Pack 2 - Minecraft Guide - IGN

Skin Pack 3 - Minecraft Guide - IGN

Skin Pack 3 - Minecraft Guide - IGN

Skin Pack 1 - Minecraft Guide - IGN