While studying advertising, Greenblatt sent comic strips to
syndicates as well as
Ad Age magazine. After graduating, Greenblatt worked as an art director on several television commercials, including
Chef Boyardee's
Chef Jr. campaign. He saw an ad from
Nickelodeon on
Animation Magazine and sent his
portfolio to them. He later received a response and became a character designer. In 1998, he landed a position as an additional storyboard artist for
SpongeBob SquarePants, before graduating to full-on writer and storyboard artist. From season 2 and 3 of
SpongeBob he teamed up with
Aaron Springer and later in season 3 he teamed up with
Kaz. After finishing up on
SpongeBob in 2005, Greenblatt became a storyboard artist on
The Grim Adventures of Billy & Mandy right after it and sister series were both split into their own shows after being together from 2001 to 2003 in
Grim & Evil. In 2007, Greenblatt began
Chowder, an animated show that he created and executive produced for
Cartoon Network. Greenblatt collaborated with
Maxwell Atoms on his new
Billy & Mandy spin-off
Halloween special called
Underfist, in which he reprised his role as
Fred Fredburger. He announced on his blog that
Nickelodeon has given the go-ahead for an 11-minute pilot for a new show created by him entitled
Bad Seeds (later renamed
Harvey Beaks). He announced in September 2013 that the show has since been picked up for 26 11-minute episodes, with production commencing at the beginning of 2014. He has also directed the
Deadman shorts for
DC Nation. On April 5, 2018, Greenblatt announced that he had now been employed by
Warner Bros. Animation, adding that he has been developing "something fun" for the studio but could not yet disclose anything else about it. On October 29, 2019, the project was officially unveiled under the title of
Jellystone!, described as a crossover of several
Hanna-Barbera characters living in the titular town "where they can't help but make trouble for one another". Greenblatt also plays Fish Taco, one of three main characters in an animated YouTube series titled
Mexiguin since 2018. He helps mentor show creator, Joe Kozdra, in animation and creative writing alongside his voice-acting contributions. On January 29, 2021, a new Greenblatt project was registered for
Disney Television Animation under the title
Unnamed Pet Resort Project. == Legacy ==