I think I'll put this in order from childhood to adulthood, since that's a reasonable structure. I will not count animated series or films, though.

Eight Childhood Favorites:

Star Wars (The whole series) -
Reasons: Star Wars was the first movie I ever saw as a child. It endeared in me a love for "Space Opera" that continues to this very day. Classic!
What would science fiction be, without Star Wars?

Battlestar Galactica (Movies and shows) -
Reasons: The second movie I ever went to see was Battlestar Galactica. Mt hero was Starbuck, and I dreamed of flying through space, fighting Cylons. Who knew it would become two truly epic series!

The Black Hole (Movie) -
For me, this is better than 2001: A Space Oddysey.
Desperate astronauts seek shelter aboard a dark ship piloted by a mad captain bent on crossing to another dimension. It inspired "Event Horizon".

Flash Gordon (The 1980 Movie) -
God, I love this movie! It has to be one of the most colorful and enjoyable Science Fiction films ever made. I watched the black and white serials on video after I saw this one, and loved them too.

Buck Rogers (The 1979 - 1981 Series) -
Given my interest in Flash Gorden, it seemed very inevitable that I would enjoy this series a lot. The casting was excellent, and most episodes were great. I had a huge crush on Princess Ardala! ;)

Wizards and Warriors (1983 Series) -
This fantasy series before Xena was even thought of, was to me a magical show. Light-hearted and fun, with a fantasy setting that truly was unique for the time. I watched every episode they made.

Return to Oz (Movie) -
As a child, I loved Fairuza Balk in this movie. I still love Fairuza Balk in films like "The Craft" so some things never change. This was Oz the way Frank L. Baum had intended it: a far darker place.

Otherworld (1985 Series) -
A show about a family trapped in a parallel world and trying to get home. I adimit, I had a thing for the Gina Sterling character, but the story of this series was really good, intelligent sci-fi.

Eight Teenage Years Favorites:

Conan the Barbarian (Movie) -
This was one powerful sword and sorcery movie. It was dark, brooding, and epic. And that is what I loved about it. James Earl Jones as Thulsa Doom, was the best villain in any of the Conan movies!

The Beastmaster (Movie) -
Not the series, not the sequals. The original! With Marc Singer as Dar. With parallels to the Mesopotamian Gilgamesh Epic, this was a fantasy film that was just something different. Awesome.

The Sword and the Sorcerer (Movie) -
Almost on par with Conan the Barbarian, this is a movie no fantasy fan should go without seeing! It isn't nearly as serious, but it is every bit as enjoyable for it's own dark universe. A classic.

Something Wicked This Way Comes (Movie) -
The horror movie that didn't need heaps of gore to be scary. It amazes me this was done in fact by Disney when they were in their dark phase. It had inspired Stephen King's "Needful Things" book.

Willow (Movie) -
This was an attempt at a live-action Lord of the Rings type of movie before the special effects of today existed. The sword fights were truly epic, especially those near the very end of the film.

Legend (Movie) -
While as a rule, I don't like Tom Cruise, this was a fantastic movie. Tim Curry played the Lord of Darkness to perfection, and the princess had a *bit* of a dark side that made her character fun.

Dune (The whole series) -
If you liked Star Wars but wished it was darker, more mature... then you will love Dune. An epic where medieval-style politics and treachery is set amidst a backdrop of huge religious conflicts.

Indiana Jones (The whole series) -
Who doesn't love Indiana Jones? My very favorite was "Raiders of the Lost Ark"; for me, the others were not nearly as good, and the newest one was the lowest point for the series, in my opinion. ;)

Eight Adulthood Favorites:

Highlander (The whole series) -
This franchise always interested me, since I saw the first movie. While the stories sometimes had huge plot holes, the concept of immortals who are battling to see who will rule humanity, is unique.

Forever Knight (The Series) -
Picture Highlander, but with vampires like unto Anne Rice's vampires. A detective trying to hide his undead nature, while the truly evil vampire who turned him into one slowly becomes his friend.

Interview with the Vampire (The Movie) -
My favorite horror film of all time, and so much better than "Queen of the Damned"! I admit it, I cried when Claudia was killed by the sunlight. The story was just that powerful and emotional.

Brahm Stoker's Dracula (The Movie) -
The best of the classic horror film remakes that were done during the 1990's. The fact that I do in fact resemble Gary Oldman doesn't hurt either.
But, truly, it is the best Dracula film ever made!

Hercules and Xena (The Series) -
I never missed an episode. I admit it, I had the biggest crush on Gabrielle; to me, she was cuter than Xena... but it was both the mythology and the humor that made it the classic show it was.

Kull the Conqueror (The Movie) -
"Conan the Destroyer" and "Red Sonja" were good, but Kull the Conqueror was more back to the real roots of the series like "Conan the Barbarian". A film about dark, evil forces and brooding heroes.

The Lord of the Rings (The whole series) -
Having grown up reading the books, I was pleased with the way these movies turned out. I liked the way the depicted all the characters, and the fact that Sauron actually made an appearance. Awesome!

Tin Man (The mini-series) -
As a fan of Return to Oz, I knew Tin Man would be very much in that style. I was pleased to see I was correct. A descendant of Dorothy fighting to save Oz from her evil sister made for a real epic!

I could list more, but this will have to suffice since it is already a long list. I suppose I have a very wide and diverse array of interests when it comes to movies and shows. It was hard to pick just eight for each category, but I feel I chose well from my all-time favorites. All, are classic.