He is the former head of animation at Rooster Teeth, a production studio in Austin, Texas, where he created the 2019 mecha web series Gen:Lock.

He is known for voice roles such as Locus and Roman Torchwick in the Rooster Teeth productions Red vs. Blue and RWBY, respectively, as well as Sanosuke Sagara in the English dub of Rurouni Kenshin, Oreldo in Pumpkin Scissors, and Yousuke Fuuma from Wedding Peach.

[3][4] He then worked on season 10 of Red vs. Blue and, in 2013, he took on a voice acting position as Roman Torchwick in Rooster Teeth's animated series, RWBY.

In 2014, Haddock co-starred in the two-hander play Venus in Fur, opposite Molly Karrasch and directed by his wife Lara Toner.

[10] In June 2019, following complaints from his former employees regarding negative working conditions, Haddock stepped down as the head of RT Animation to fulfill a strictly creative role.