Doctor Who: 30 NuWho Characters Who Would've Made Fantastic Full-Time Companions
7. Mickey Smith
Appeared in: Various (Series 1, 2, 4, & The End of Time: Part 2)
From being labelled "Mickey the idiot", proclaiming himself the "tin dog", to defender of the Earth, Noel Clarke's character is the one who has developed the most in this list.
Nevertheless, even during his earlier "idiot" years, Mickey did save the day with a big yellow truck in The Parting of the Ways, and with his hacking skills in World War Three and The Age of Steel, whilst also saving the Tenth Doctor's suit in that one - which is no small matter. That latter episode was the major turning point for Mickey, as he decided to stay on the parallel world by liberating it from the Cyber factories, and looking after his grandma. It also showed he was no longer reliant on Rose anymore.
Eventually, Mickey found love with Martha. It's a shame that due to other filming commitments, both Clarke and Freema Agyeman weren't available for the excellent Children of Earth. There's definitely scope for a Big Finish audio adventure at the very least...