If anyone ever asks me what my all-time favorite piece of Ninja Turtle artwork is, my answer will always be this piece by Michael Dooney:
Originally created as a new cover for the second printing of TMNT (Vol. 1) #4 (recreating the original Peter Laird cover), it would eventually become one of the most reused pieces of art within TMNT merchandising.
If you recognize it from anything, it's most certainly as the box artwork for the first NES TMNT game by Konami:
The art would go on to be used for Tiger Electronics handheld games, on cabinets for Konami's TMNT Arcade game and just about every place else. Thanks to being recycled for merchandising to such a vast extent, it's easily one of the most recognizable bits of Turtle art ever, not to mention one of the best.
There's so much kinetic energy going on in that print, the art nearly leaps off the page and nunchakus you right in the face. And knowing that it was hand-painted the ole fashioned way and not with computers only makes it that much more impressive.