The move, announced late on Sunday, follows Goldner's statement last year that he had been under continued medical treatment following his cancer diagnosis in 2014.
Stoddart, the CEO of marketing firm InnerWorkings Inc until last year, takes the position at a time when Hasbro is battling industry-wide supply-chain issues to ensure its toys hit store shelves in time for the pivotal holiday season.
Long-time CEO Goldner's medical leave is a "big shock" but will likely not impact Hasbro's ability to execute its strategy of focusing more on boosting its entertainment and licensing business, Jefferies analysts said in a note.
Other high-profile CEOs that have stepped away from day-to-day management for medical reasons include JPMorgan Chase & Co's Jamie Dimon, who had an emergency heart surgery in 2020, and Altria Group Inc's Howard Willard after he contracted COVID-19 last year.
Apple Inc's Steve Jobs had also taken medical leave in 2011 as he battled pancreatic cancer.
(Reporting by Deborah Sophia in Bengaluru; Editing by Aditya Soni)