[The Squatter of Amon Rûdh]

So it is Gandalf. I'd guess that 'former agent' is 'ex man' or 'X-Man', and Metal Head is Professor X, played by Patrick Stewart. Of course Gandalf and Dynamo were played by the same actor: Sir Ian McKellan. As for nearly being an agent, I don't know enough about the X-Men universe or remember enough about the films to hazard a guess.