Nelson Yomtov is the colorist of every single issue of the original Marvel US Transformers comic book. He is sometimes credited as Nel Yomtov.
He was also a colorist for Fantastic Four.
Discerning readers can find numerous instances of coloring errors among Yomtov's pages, as well as, perhaps, an over-use of the technique of coloring panel backgrounds (including background characters) uniformly. Yomtov has been quoted as saying that it was quite a challenge to keep up with all the new characters that were constantly being introduced at Hasbro's insistence.
The most notable such error, assuming it was not intentional, was his recoloring Emirate Xaaron to be entirely yellow, as opposed to the gold/silver/black colors he was given in UK comics. Upon appearing for the first time in a Marvel US issue, Xaaron kept this all-yellow scheme throughout the remainder of the series.