Mazinger Z
The shows spawned so-called "team-up movies" early on, which were like longer episodes that teamed up Mazinger Z with one of Go Nagai's other creations, as in "Mazinger Z vs. Devilman" (マジンガーZ対デビルマン) in 1973 as well as "Mazinger Z Vs. Dr. Hell" (マジンガーＺ対ドクターヘル) and "Mazinger Z Vs. The Great General of Darkness" (マジンガーZ対暗黒大将軍) both released in 1974.