Despite an otherwise staggering variety in his work, there does seem to be a bit of a recurring theme: (in chronological order) David Tennant in The Bill: Deadline (1995), Secret Smile (2005), The Friday Night Project (2007), Doctor Who: Planet of the Ood (2008), Doctor Who: Forest of the Dead (2009), Hamlet (2009), St Trinian’s 2 (2009), Doctor Who: End of Time (2010), Nativity 2 (2012), The Escape Artist (2013)
Improved version of my previous post, because I forgot one of the most important examples. (Many thanks to reconditarmonia for pointing it out to me!)
David Tennant as Steven Clemmings in Deadline an episode of UK drama series The Bill.
This can be watched on Youtube. And if you want to see David portray someone with psychopathic tendencies, who can easily make you want to hate him with just a simple glance, or the way he says something like poisonous venom dripping from the fangs of snake ready to bite its victim, and yet can still manage to charm you into wanting to trust him–Then this you need to, no, you must watch.