The Discovery Channel Mini SeriesDragons: A Fantasy Made Real is a Mockumentary all about how dragons could be scientifically possible. There are four types of dragons covered: Prehistoric Dragons, Marine Dragons (Sea Monsters), Forest Dragons (Chinese Dragons), and Mountain Dragons (European Dragons). There are also "Desert Dragon" shown but it was never elaborated upon.
Along those same lines, Sci-Fi's Beast Legends makes a dragon from a mix of real animal parts, and ends up with a creature resembling the Kaiju Varan about the size of a bull.
In Knightmare there seem to be three different types of Western style dragons, based on color. The smallest and weakest are blue and are never actually seen, just mentioned. Greens are the friendliest (in the sense that they are willing to deal at all with humans). Red dragons are both the most powerful and most wildly destructive.
The (male) dragon lives under the castle in a cave, can talk and knows magic. It can only be controlled by a dragonlord, a people of which Merlin is the last. Dragons are also only born with the help of a dragonlord, who calls them from the egg by naming them.
The episode Eye of the Phoenix has Wyverns. They are a lot smaller and act more like a pack of intelligent, but not sentient, animals. Gwaine mentions that they are distant cousins of the dragons, but it seems wyverns are at least closely related enough that a dragonlord may command them.
In Lost Tapes a "Dragon" appears, but as a variant of the Real Life Komodo Dragon that was thought to be extinct: the Megalania. It eats a Survivor Man wannabe.
Special Unit 2 references European and Asiatic dragons, and prominently features a "Native American" dragon. However, it acts like (and vaguely resembles) the stereotypical European portrayal in terms of behavior, is armored like a Tank and has a taste for gnomes.
Kamen Rider has had four dragon-featuring seasons so far:
Kamen Rider Agito is a Chinese dragon based humanoid and the show implies that humans will become like Agito.
In the tv series version of The Dresden Files a dragon appears in one episode and it's strongly hinted that a member of the White Council is one in human disguise.
In Primeval (Season 3, Episode 7), a dinosaur known as a Dracorex wanders through an anomaly into the middle ages, where it is mistaken for a dragon.
Supernatural's budget constraints gave us dragons that could shift between human and dragon forms, and apparently they prefer to be in human form most of the time. Naturally they have heat-based powers, which they use to french fry their victims. They can only be killed by swords forged in Dragonblood, and they work for the progenitor of all monsters, Eve.
One season 10 episode of Stargate SG-1 had a dragon attack the motley crew (SG-1, Ba'al, and Adria) searching for Merlin's anti-ascended being weapon. This dragon was actually a sophisticated technological illusion; beating it required Daniel yelling its creator's name at it.
"Different" doesn't really begin to cover the titular character in H.R. Pufnstuf.
An episode of Sliders has the heroes slide into a world where magic is possible (much to Professor Arturo's chagrin). The villain in the episode is an Evil Sorcerer who had the Mallory Clan wiped out due to a prophecy that he will be killed by a Mallory. During the climax, he turns into a dragon (not much larger than a human) and starts spitting fireballs at heroes. Rembrandt tries to grab the only sword capable of slaying him/it but can't move it. The sorcerer's student explains that only a Mallory can take the sword. Cue Quinn grabbing the sword and stabbing the dragon/sorcerer.