'The Walking Dead' zombies have steadily decayed over six seasons — here's how they've changed

Every season on "The Walking Dead" we're introduced to new characters, new threats, and tons of new zombies who only continue to get more gruesome.

Though the show has been on the air since 2010, only about two years have transpired in the zombie apocalypse, according to executive producer and make-up supervisor Greg Nicotero. 

That's helped slow down the decaying process a bit, but Nicotero and his visual effects crew continue to evolve the look of the walkers, as they're referred on the hit AMC series, each year.

"Every season we take advantage of the advancement of our timeline," Nicotero recently told Tech Insider. "It's definitely something that we try to push in terms of more skeletal [looks], sloughing off skin, missing noses, exposed ribs, exposed organs, all that stuff. Anything that we can do to further and continually suggest that these are walking, emaciated, decomposing corpses that have been wandering around in the sun, wandering around in the rain, wandering around in the elements for almost two years now." 

While many walkers may be missing limbs now, they didn't always look this frightening.

Keep reading to see how zombies on "The Walking Dead" transformed over the course of six seasons.

In season one, we're introduced to the zombie apocalypse about four to five weeks after it has begun.

Clothes are pretty much intact, and from far away, most zombies could pass for regular people.

Special effects makeup artist and current executive producer Greg Nicotero and his team from KNB EFX used Robert Kirkman's graphic novel for inspiration.