I made a boring Thundercracker (so, basically a Starscream, with some very, very minor aesthetic changes). The IDW comics have turned him into my favourite Decepticon, so I just had to make him.
After that, I wanted to have a try at making some Beast Wars characters (before they got their beast modes, of course), I found some images online to use as reference material, and made an Optimus Primal (a Scientist), and Rattrap, who's my Infiltrator, not that I've started levelling him yet. Too busy with the Scientists. I'm also working on a Beast Wars Megatron, which is a work in progress.