Requiring an HQ choice for Space Marines seems counter intuitive, since in most of the books I have read about them, they are never deployed in groups greater than squads, invariably lead by a grizzled sergeant who would surely have a cigar hanging from clenched teeth.
For the Halo themed army I am building from ActionClix figures, there is really only one figure that stands alone from the crowd...Spartan John-117, the Master Chief. Here is the figure I have for him:
Then I thought to look through the Space Marine Special Characters. I almost decided on Shrike again, since the 'same weapon on both hands' shoe fits, but I demurred, simply because even I cannot bring myself to say those count as lightning claws. Also, the Chief has nothing that looks like a Jump Pack.
Then, I found it...