Igor

Igor is a Decepticon who lives in Megatron's scrap yard based refugee camp in Africa, where he happily cheers for Megatron while chewing on some metal chips, and sometimes even the Scalpels that repair Megatron.

Dark of the Moon film
Igor traveled with his Master to Washington D.C. Megatron went to the Lincoln memorial where he destroyed the statue of Abraham Lincoln with his "Shotgun" and seated himself on the Memorial's chair as a throne. After the broken pieces rolled down the steps, Igor gnawed happily on its disembodied head.

While in D.C, Megatron, Starscream and Igor met up with, the now revealed Autobot traitor, Sentinel Prime. After Sentinel activated the Space bridge, Megatron launched his invasion. Igor started jumping with joy and cheering for his master.

Afterwards, he seems to disappear in typical fashion.

Dark of the Moon comic adaptation
Igor stays in Megatron's refugee camp in Namibia, Africa. When Starscream arrives and starts grovelling, he isn't to happy, hey shouts "NO! My master! Mine!". Igor accompanied his master to Washington were Megatron launches his invasion. He also goes to Chicago. After the the battle, he was seen staring up at the sky, wondering what had become of his master.