1. Mothra (1961)
1962 U.S. theatrical poster
What It’s About: Infant Island’s kaiju protector retaliates against atomic testing and the kidnapping of the Shobijin (“small beauties”).
Why It’s Unique: Filled with wonder, beauty, and mysticism, Mothra’s introduction is essential viewing.
Favorite Scene: The Shobijin’s “dinner show” featuring the famous Mothra song is entrancing, but watching Mothra emerge from her cocoon in her full winged glory is even better.
Watch the original trailer here.
2. Rodan (1956)
Japanese theatrical poster
What It’s About: Giant pteranodons awaken and wreak havoc.
Why It’s Unique: Another great kaiju introduction, made even better by the suspenseful plight of miners being attacked by giant insects.
Favorite Scene: I love kaiju films that build the tension as long as possible before the first reveal, and Rodan manages to build for 45 minutes before the flying beast appears.
Watch the original trailer here.
3. War of the Gargantuas (1966)
French theatrical poster
What It’s About: In this sequel to Frankenstein Conquers the World (1965), which almost made the list, humanoid kaiju Gaira and Sanda battle in all kinds of terrain, from mountainside to city.
Why It’s Unique: Humanoid kaiju allow for some great battle scenes and highlight the detail of the wonderful forest and mountain miniatures.
Favorite Scene: I’m a fan of all the Maser Cannons used in the film, but the “shock” scene winner has to be Gaira casually swallowing a woman whole, then spitting out the bouquet of flowers she was holding.
Watch the trailer here.
4. Gamera (1965)
Japanese theatrical poster
What It’s About: A prehistoric giant turtle who consumes fire and flies with rocket power must be stopped.
Why It’s Unique: The first film of the second most popular kaiju series has a serious tone—unlike the rest of the franchise, aimed squarely at children—and features wonderful effects.
Favorite Scene: While Gamera destroys a ship stuck in the ice, tiny animated figures run away from the wreckage. Also, as Gamera stomps through the city, people can be seen running by in building windows (achieved with a filmstrip-like effect).
Watch the original trailer here.
5. Gamera: Guardian of the Universe (1995)
Japanese theatrical poster
What It’s About: Through a mystical bond with a young girl, Gamera awakes to defend Earth against his ancient foe, Gyaos.
Why It’s Unique: Gamera’s first Heisei film features incredible effects and a more mature tone, so this is a great one to show your friends who don’t “get” kaiju.
Favorite Scene: In the middle of fantastic fighting and destruction effects, watching poor Asagi (the young girl mentioned above) feel Gamera’s pain is intense!
Watch the trailers here.
___________________________________
Parts one and two of Destroy All Computer Generated Monsters are here and here, respectively.
Movie poster image credits: Wrong Side of the Art, Godzilla Wikia, Wrong Side of the Art, Movie Poster Shop, and Wikipedia
2 Warps to Neptune 
Editor’s note: The “what it’s about” for Gamera? Best kaiju movie description ever!
“War of the Gargantuas” has got to be the best looking kaiju film out there. I’m looking forward to getting an HD copy of that one to go with my “Frankenstein Conquers the World”.