On Comic Book Resources' Comics Should Be Good site, Kieron Gillen (basically Marvel's James Roberts, who recentlyish brought Death's Head back to the Marvel Universe), names Impactor as one of the top five British comics characters here.

5. IMPACTOR

Impactor also follows on from Hook Jaw, but only because he’s got a hook in his anatomy which he stabs into things. Impactor is a supporting character created by Simon Furman as part of the British-originated Transformer Comics. And – no, shut up. You have no idea how important the Brit TF comics were to a generation. Impactor debuted in TARGET 2006, which was where Furman’s Transformer’s saga – er – transformed. It had been good before – TARGET 2006 was immediately preceded by IN THE NATIONAL INTEREST, which married government-agency paranoia to enormous saurian robots – but this new storyline was something else entirely. The game was raised, the toys played with so hard they broke. In a periodic comic, the sudden sense of freedom in the rush from week to week was overwhelming. We revelled in it. The next issue panel that only displayed the head of the insectoid bad-guy Shrapnel being shot clear through by some manner of brutal harpoon MUCH LIKE THE ONE HOOK-JAW MAY HAVE USED seemed like a call to arms, a statement that anything goes. Seven days from first seeing it, you couldn’t have kept me away from the newsagents with riot police.

Impactor went on to sacrifice himself to save everyone at the end of the story. Then a few years later, he returned in an ahead-of-its-time zombie story as a zombie-robot, and was the one character to overcome his re-animation, before swiftly proceeding to sacrifice himself to save everyone again. What a bot! For the rest of the run, Springer keeps on worrying about not being good enough to replace Impactor as the leader of his squad of robo-commandos. And rightly so, Springer. Compared to Impactor, you’re shit.

In short: Impactor is basically who Brit-kids got sniffly over instead of Jean Grey. Jean Grey didn’t even have a harpoon for a hand.