DC's Legends of Tomorrow, or simply Legends of Tomorrow, is an American superhero action-adventure television series developed by Greg Berlanti, Marc Guggenheim, Andrew Kreisberg, and Phil Klemmer, who are also executive producers along with Sarah Schechter and Chris Fedak; Klemmer and Fedak serve as showrunners. The series, based on the characters of DC Comics, airs on The CW and is a spin-off from Arrow and The Flash, existing in the same fictional universe. The series premiered on January 21, 2016. In January 2017, The CW renewed the series for a third season, which is scheduled to debut on October 10, 2017.

When does dc legends of tomorrow come out? Okie... think carefully first, then make a decision:
To answer this question, we should know that: The series premiered on January 21, 2016. So, the answer is January 21 , 2016.