Shoguns Ninja and Revenge of the Ninja
Damn i love ninjas. Especially cheesy ninja 80's movies. I remember as a kid popping in a ninja vhs flick one saturday morning watching it 2 or 3 times then I would go outside and try to work on my ninja moves. I talked my Dad into getting me a bunch of stars, nunchucks, blow darts and throwing knives. After about 4 hits to my own head learning the nunchucks i threw those away and stayed with the throwing weapons. I got pretty good with the knives but lost most of my stars after throwing them at trees in the woods. Here in my opinion are the best of the best of ninja movies.
Shoguns Ninja starring Sonny Chiba as Shogun himself and Henry Sanada as Takamaru Mamoichi. The movie starts with Takamaru's clan gets destroyed by Shogun and his henchmen while Takamaru as a little kid escapes by boat. Apparently he practices fighting and comes back grown up looking to bring back the Mamoichi clan and destroy Shogun. The movie has a lot of fantasy elements to it with some awesome weapon and kung fu fighting thrown in. There are spider ninja, mole ninja, people being boiled alive and one of the most painful (for men at least) torture scenes ive seen in a movie. I almost forgot there is a white haired master, two mute henchmen, a crazy fire dance sequence and a cool training sequence. The finale fight is insane with a battle in a rock quarry and in a forest with all kinds of booby traps. The only negative i had first watching it was the music. Its 70's acid jazz and totally strange for this kind of movie. By the end of the movie i was digging it and i think it adds to the charm. Highly recommended.
The only other ninja movie i think i saw more than Shoguns Ninja was Revenge of the Ninja starring Sho Kosugi. Sho Kosugi was the king of ninja movies with about 7 ninja movies under his belt and a short lived ninja tv series call The Master. From start to finish this movie is action packed with some serious ass kicking. I dont want to give too much away but Sho's family is killed at the beginning of the movie by some rival ninja who for some unknown reason want to kill the clan. Its not a period piece but based in the 80's with cheesy clothes and hairdo's abound. Sho takes his son and mother with him to America to start life over. He starts a china doll business with his American friend Braden. Sho's son on the movie and in real life Kane Kosugi on accident discovers that Braden is smuggling cocaine in the dolls. While this is happening there is an evil ninja that is killing crime bosses all over town. Kane Kosugi as a little kid (about 6 maybe) has some cool but unrealistic fights as he's kidnapped so he can be kept silent. Sho finds out about this and has to battle some thugs that are stealing his merchandise in a cool scene at a play ground. Sho kicks all kind of ass and then has to collect himself so he can rescue his son and fight the evil ninja. There is a cop friend that is also a black belt that he gets to help him out. He vowed to never don the ninja gear and sword again. But he is forced to take desperate measures and unleash vengeance to stop all the madness and to keep his family intact. Anyways there are many cheesy lines like the ones i just said all over this movie. The actors are bad but the music does actually still hold up in comparison to a lot of other 80's movies. Swords, blow darts, smoke bombs, stars, nunchucks, fake arms, cheesy silver mask, sickles with ropes, uzi's and anything else you can think of are in full display. There is a long finale battle at the top of a building that brings it all to a fitting end. Another movie i recommend to kick back and enjoy with some brew and friends. Both of these are highly recommeded and make sure you remember "Only a Ninja can stop a Ninja"

Heres a trailer for Revenge of the Ninja