Well, not sure if these will fit, but there is a planet series of Heuchera, from Europe, I think. Among others, there is Heuchera 'Mars, Heuchera 'Venus' and Heuchera 'Saturn.'
This is more Twilight Zoneish, than Sci Fi, but there is a hosta called 'Elvis Lives.'
This is challenging.

There is a whole series of daylilies that start with Jedi. Just today I found a tree peony called "Companion of Serenity". If that one weren't $70 I would have bought it in a heartbeat. There was also Daedalus and a few others with mythical names but all still very pricy.

There is a pulmonaria that I might have seen at Terranova Nurseries' website called something like "Dark Vader." A play on words instead of a true cultivar name, but it might be a nice addition!

Thanks all-I do have 'Jedi Dot Pierce'. Haven't seen any other Jedi's though. I've posted on the Daylily, Rose and Annual forums. If anyone is interested both the daylily and rose forums have come up with lots of names.

There must be thousands, especially with SciFi movie ties. Here's a small sample:

Epicactus epiphyllum 'Jedi' (zone 10)
Hibiscus rosa-sinensis 'Star Wars' (zone 9)
Hibiscus rosa-sinensis 'Space Ship' (zone 9)
Hibiscus rosa-sinensis 'Batman' (zone 9)
Hibiscus rosa-sinensis 'E.T.' (zone 9)
Hibiscus rosa-sinensis 'Empire' (zone 9)
Hemerocallis 'Alien'
Hemerocallis 'Atlantis'
Hemerocallis 'Batman'
Hemerocallis 'Empire'
Hemerocallis 'Empire Star'
Hemerocallis 'Firestarter'
Hemerocallis 'Godzilla'
Hemerocallis 'Kahn'
Hemerocallis 'Matrix'
Hemerocallis 'Ming'
Hemerocallis 'Skywalker'
Hemerocallis 'Space Ship'
Hemerocallis 'Star Wars'
Hemerocallis 'Yoda'
Hosta 'Atlantis'
Hosta 'Godzilla'
Hosta 'Leviathan'
Hosta 'Matrix'
Hosta 'Outer Space'
Hosta 'Terminator'
Tomato 'Empire'
Tomato 'Galaxy'
Tomato 'Matrix'
Tomato 'Mingo'
Tomato 'Superman'
Tomato 'Vulcan'
Tomato 'Zena'
Iris 'Superman'
Iris 'Batman'
Iris 'Skywalker'
Iris 'Matrix'
Iris 'Ming'
Iris 'Firestarter'
Iris 'Godzilla'
Iris 'Critter'
Cauliflower 'Skywalker'
Flowering Crabapple 'Kirk'
Canna x generalis 'Empire'
Canna x generalis 'King Kong'
Canna 'Spiderman'
Apple 'Empire'
Strawberry 'Empire'
Lettuce 'Empire'
Sweet Corn 'Empire'
Potato 'Empire'
Melon 'Alien'
Floribunda Rose 'Atlantis'
Hardy Water Lily 'Leviathan'
Onion 'Predator'
Asiatic Lily 'Matrix'
Watermelon 'Matrix'
Echinopsis 'King Kong'
Triumph Tulip 'King Kong'

Lilies Stargazer and Starfighter--both beautiful.

WOW donn thanks for the great list. Looks like I'm really going to be able to do this garden.

There are also some stargate daylilies....ie stargate portal

I thought about getting the first one (a few years ago, there have since been others added) but I balked at the price.

~Chills

There are also hostas "Enterprise," a sport of Capt. Kirk, and "Spock's Ears."

Viola 'Mars' and the dozens of Spacecoast Hemerocallis come to mind.

Knautia macedonica 'Mars Midget'
Potentilla atrosanguinea 'Vulcan'

Isn't there a Sunflower called "Kong", or "King Kong"?

I saw ajuga 'planet zork' in Plant Delights' catalog.

And let's not forget Rhododendron 'Mars' and'Vulcan's Flame'. . .

Here are some more pretties to consider:

Iris 'Starship Enterprise' (Tall Bearded)
http://davesgarden.com/pf/showimage/75412/

Iris 'Dark Vader' (Standard Dwarf Bearded)
http://davesgarden.com/pf/showimage/146495/

Iris 'Jurassic Park' (Tall Bearded)
http://davesgarden.com/pf/showimage/43022/

Iris 'Starwoman' (Intermediate Bearded)
http://hortiplex.gardenweb.com/plants/p1/gw1088155.html

Iris 'Alien Mist' (Tall Bearded)
http://davesgarden.com/pf/showimage/22381/

Iris 'Battlestar' (Tall Bearded)

Iris 'Bermuda Triangle' (Border Bearded)
http://www.medianiris.com/images/Conventions/BB/Bermuda%20Triangle.jpg

Can you tell I've been looking at irises, lately?? Have fun with your theme!

I believe theres also a "Vulcan" Lychnis.
CMK

This has been a big help. I'm planning the garden for next year now I have a head start...

Mariann

Hostal Enterprise and Vulcan, which are related to the Captain Kirk.

Hey Galium! How's that Sci-fi garden coming along? I wanna see!!!

tasymo-Thanks for asking. I'm still trying to collect plants for the garden. I'll get there eventually.LOL I will certainly post pictures when I do.
Mariann

Coreopis 'Flying Saucers'

Coleus 'Saturn'.

May The Force be with you.

There is also an Echinacea called Mars and one called Harvest Moon.