Spectreman

Spectreman was a 1971-1972 toku show from P Productions.

Banished from the peaceful simian Planet E, the mad scientist Dr. Gori and his brutish assistant Karras (Lla in the Japanese version, as in "gorilla") search for a new planet to rule after Gori's plot to conquer Planet E had been foiled by its government. Coming across the Earth, Gori is captivated by its beauty, but is appalled by its inhabitants' misuse of its environment, leading to severe pollution (a huge topic back when this series was made), so mankind must be quickly conquered if this planet is to be inhabitable, so he plots to, ironically, use the very same pollution that's plaguing the Earth to create horrible giant rampaging monsters to wipe out and/or enslave mankind.

Fortunately, hope comes in the form of the Nebula 71 Star, a Saturn-like artificial satellite that observes the Earth incognito. Fearing that Gori may eventually make the Earth uninhabitable, they dispatch Spectreman, their super-cyborg agent, to battle the menace of the mad apeman. Spectreman disguises himself as a Japanese man named Jôji Gamô to walk among the humans and scout out Gori's weekly menace for the Nebula 71 Star. He works with a government-run group called the Pollution G-Men, run by Chief Kurata. This group investigates phenomena involving pollution, but they don't (until late in the show's run) have the facilities to handle giant monsters, so unbeknownst to them, their comical-yet-mysterious teammate Jòji disappears on them, only to help them as Spectreman!

Tropes used in Spectreman include:

The Ace: Gamo Joji, and it pisses everyone off on the team.
Chuck Cunningham Syndrome: Rie Endo vanished after episode 10 for reasons that are hard to tell.
Da Chief: Played by Toru Ohira in a live-action role.
Expy: Gori and Karras are evil exceptions from an all-pacific intelligent simian race, just like DC Comics' villain Gorilla Grodd. Karras shares appearance and strength with Grodd, while Gori is similar to Grodd in intelligence. Planet E, homeland of highly evolved, pacific apes, shares similarities with Gorilla City.
Green Aesop: Very much so in the first half.
George Jetson Job Security: Joji Gamo essentially hired himself to be on the G-Men team. He is fired and re-hired almost every episode.
Hey, It's That Voice!: Seizo Kato voices Gori in the early episodes.
Jerk with a Heart of Gold: Perhaps the first toku hero who is like this...
No One Gets Left Behind: Spectreman would sometimes get in trouble with his boss over his position to save everyone he possibly could, while Nebula was willing to sacrifice a few people here and there to avert bigger tragedies.
Power Limiter: Unlike a lot of tokusatsu, Spectreman actually has no ability to control his own transformations. Nebula decides when he is and isn't to change to his giant super-powered self.
Shout-Out: The Powerpuff Girls gave a huge one to this show with Mojo Jojo.
Spotlight-Stealing Title: In Japan, the show's original title was Uchū Enjin Gori (Gori the Space Ape), which was then changed to Gori vs. Spectreman in Episode 21 and then to just Spectreman in Episode 40 for the remainder of the series.
Villain Song: The first ending is Gori's theme.