Now he's turned his attention to Donald Trump and his new best friend Sean Hannity, who last week was revealed as the 'mystery client' of Trump's personal attorney Michael Cohen.
It was also revealed that Hannity is almost in constant contact with the president and is practically considered to be a White House staff member.
This is problematic for numerous reasons that we won't list in their entirety, but the fact that Trump is potentially getting a lot of his advise from a Fox News journalist is worrying.
Now to the point. Trump has a big decision to make in the next few weeks as by 12 May he will have to rectify the Iran Nuclear Deal.
The deal was struck by the Obama administration in 2015 along with the British, Chinese, Russian, French and German governments and allowed Iran to trade on the open market. In exchange, they would not enrich their uranium to weapons for 15 years.
However, Trump is famously not a fan of the deal and has tweeted about it on more than one occasion.
Needless to say, it doesn't look like Trump will be attempting to improve this deal. Furthermore, some of his top advisers, CIA Director Mike Pompeo, National Security Advisor John Bolton and - you guessed it - Sean Hannity aren't supporters of it either.
Noticing that there could be a problem here, Oliver has stepped in and is attempting to sway Trump's decision with an advert that will run during Hannity's show in the DC area, which Trump watches religiously.
Two of Trump’s top advisers are, like him, dead set against this deal, and they’re getting backup from Sean Hannity, whose show the president watches so much, advisers refer to him as the ‘shadow chief of staff'.
Hannity hates this deal too, so there is not really a way for us to get a moderating voice into this conversation short of buying time on Hannity’s show this week and running an ad like this.
Cut to an ad of Catheter Cowboy, a recurring character on the show, interrupting a family meal to explain why protecting the Iran deal is actually a pretty good idea for most of mankind.