It isnly only villains and unlikable characters who are slated to die horribly in SWAT Kats. So it is with your friend and mine, Dr. N. Zyme. He's a scientist who works at Megakat Biochemical Labs. Although none of this would be established until much, much later in season two, Zyme was once the colleague and employer of the villainous Dr. Viper back when Viper was still Dr. Elrod Purvis and came across as a very kindhearted, sweet guy.
But since that all came later, and, at the time of his death, Zyme was just an expendable one-episode character, the writers felt free to give him that most classic of death scenes, the "Stand there and go 'Aaghhhhh!' and then dramatically cut away while the monster reaches for you" scene.
When Dr. Viper creates a slew of giant purple bacteria monsters by mutating another villain named Morbulus, which divide like giant amoebas whenever they're hit with conventional weaponry, he sets them to go and attack Megakat Biochemical so he can steal a rare chemical called Katalyst 99 for reasons never gone into.
Commander Feral comes to Dr. Zyme for assistance. Zyme is somehow able to determine with minimal investigation that the creatures are "giant bacteria" and gives Feral a massive quantity of powerful antibiotics in a gigantic hypodermic needle (!). After the SWAT Kats kill one of the creatures using electricity, Feral confidently uses Zyme's weapon on the remaining monster while Zyme and Callie Briggs look on from inside the lab.
At first it seems like it's working, since the bacteria monster begins to turn brown and shrivel up.
This is cause for much celebration for Zyme.
But then Dr. Viper to rain on his old boss' parade. "My bacteria isss immune to antibioticsss!" he hisses.
Sure enough, the hardened, dried up "shell" around the now statue-like monster begins to crumble and fall away. Then it turns and smashes its hand through the window.
Two problems with this scenario. Firstly, earlier, Zyme had reassured a nervous Callie that the windows were "practically indestructible." But the monster's hand barely nudges the glass before breaking it! Sheesh! Secondly, even though Callie sees the monster turning to do this, she not only shouts no warning to Zyme, who has his back to the window because he's focused on Viper, but when the glass breaks, she just turns and runs, essentially unheroically abandoning Dr. Zyme to end up as monster kibble.
True, she could've reasonably assumed he'd follow her example, but a simple "Dr. Zyme, look out!" followed by grabbing his arm and dragging him after her could've averted one of the cruelest deaths in the series, and in an episode already bursting at the seams with them.
Anyway, Callie runs while Zyme just turns, throws his arms up, and goes "Aaahhhhh!" as the big gooey purple hand descends down over him.
His death isn't actually seen, only implied, and, added to the confusion, the animators for some reason added yellow eyes to the hand as though to make it resemble the monster's mouth, and, weirder still, right as he is about to be entirely engulfed or grabbed or whatever, we cut to an exterior view of the building whereupon the monster seems to abandon its attempt to get Zyme so it can turn and try unsuccessfully to grab Feral's helicopter, implying there is a very brief window wherein Zyme could've survived. Nonetheless, he disappears from the episode entirely, with his only other appearance in the series being a posthumous flashback episode in season two, and he is apparently officially listed as dead as far as the series creators and writers are concerned.
Had Zyme remained a non-entity who just happened to have an interesting name pun, and never appeared again, it's doubtful anyone would find his apparent demise here particularly cruel or unjust of the writers, however since he got so much character development later on, it therefore seems like his death here is particularly callous and mean-spirited, especially since it's so sudden and nothing is done to either warn him of the attack and not even the most minor effort is expended by the usually very selfless and heroic Callie to save him.