Valkyrie was introduced to the team in issue #4 (February 1973). Writer Steve Englehart has stated that he added the Valkyrie to the Defenders "to provide some texture to the group." Englehart wrote "The Avengers–Defenders War" crossover in "The Avengers" #116–118 (October–December 1973) and "The Defenders" #9–11 (October–December 1973), leaving "The Defenders" afterwards because he "didn't want to keep doing two team books at the same time." Len Wein briefly wrote the series and introduced such characters as Alpha the Ultimate Mutant and the Wrecking Crew. Wein also added Nighthawk to the cast because, in his words, doing so "gave me a character to play with who didn't have a whole lot of previous history ... [a character I could do anything I wanted to without worrying about how it would affect any other titles that character might appear in." He later became the editor for several issues.