Commander 'Awesome' Lasky, at his post.
Commander Awesome was second-in-command of the Infinity after Captain Del Fail until Fleetcom realised Del Fail is a complete retard and thus Commander Awesome replaced him as Captain. His real name is Lasky, but he gained the nickname Commander Awesome because he is such a badass. And, to top things off, he DOESN'T die! How awesome is that!
He initially started out as a pathetic weakling of a recruit, but he soon met Johnny who kicked him into shape and taught him how to be a man. Since then, he's been transferred from ship to ship, travelling up the ranks on a one-way trip to the top.
So why on Earth did he end up on a rust-bucket like the Infinity? Well, allegedly it was a conspiricy by the brass to assign naval personell who showed the potential to possibly replace them as admirals to ships that were doomed to die. But, against all odds, Lasky survived. It was after the Battle of Requiem that he gained the nickname 'Commander Awesome'.
Commander Awesome with his uber-one shot pistol
Commander Awesome took over the Infinity from the disgraced Captain Del Wailing Failure and preceeded to kick the arses of every living thing on the planet, from Covenant to Prometheans. He then metaphorically spat on their graves and danced on the ashes of their corpses (that last one was no metaphor, seriously, its on Youtube).
When he returned home, he was immidietly awarded the giant medal for being awesome and wearing assorted armour and getting all the babes and saving the hero and destroying the enemy planet and randomly disappearing on the level with the mammoth, which he proudly displayed on his face. Such a medal had never been awarded before since the criteria were so specific, so Commander Awesome was given Supreme Command over the UNSC in the wake of the Death of Lord Hood, carried out by Johnny in Commander Awesome's abscense.
Another interesting fact about Lasky is that he is the only member of the UNSC to ever retain the amazing pistols that they had on board the Pillar of Autumn. After Lord Hood realised that these pistols were amazingly powerful and could destroy anything, he withdrew them as part of a conspiracy to make humanity lose the war and therefore give him more power. Commander Awesome hid his pistol and so therefore retained the design, and he hopes to re-introduce it back into the UNSC arsenal. If he does, scientists believe that the UNSC's MAC cannons will be made redundant as all ship can be armed with these pistols as they one-shot anything.