The streets are packed with conventioneers, many dressed as iconic film and TV characters. And the hotels are at capacity. If Mary and Joseph were unlucky enough to ride into town for Comic-Con's "preview night", they would find no room at the inn.

Though it was born as a bona fide comic book convention in 1970 - a pastime which still commands a chunk of the convention floorspace to this day - Comic-Con has become one of the most important dates on the film and television marketing calendar.

There is also no shortage of Australians on display, with a slew of stars in attendance, including Gigi Edgley (Jim Henson's Creature Shop Challenge), Luke Mitchell (Marvel's Agents of Shield), Travis Fimmel (Vikings) and Emilie de Ravin and Georgina Haig (Once Upon A Time).

To that list you can add Hugh Jackman (Pan), Julian McMahon, Daisy Betts and Yael Stone (Childhood's End), Eliza Taylor and Bob Morley (The 100), Dominic Purcell (DC's Legends of Tomorrow), Jenna Lind (Spartacus), Stephen Dunlevy (Mad Max: Fury Road) and Bella Heathcote (Pride and Prejudice and Zombies).

There are even a few Kiwis thrown in for good measure, including Manu Bennett (Spartacus), Marton Csokas (Into The Badlands), Rose McIver (iZombie) and Lucy Lawless (Ash vs. Evil Dead).

It's difficult to get a sense of the convention until it is fully underway, but two things are clear from the so-called "preview night": this is the year that TV is king, and Lego's Big Bang Theory kit has already staked a claim on the convention's most in-demand toy.

Television will take the main stage this year, largely because some of the key players in American cinema are absent. Marvel is not in attendance, choosing instead to focus on Disney's D23 Expo, which is being held in August.

And Paramount is also not attending, largely because its key Comic-Con titles - including the third Star Trek film - are only just commencing production and would be better showcased next year.

That doesn't mean big ticket cinema is entirely missing. A planned panel in the convention's largest space - Hall H - for the upcoming Star Wars film, Star Wars Episode VII: The Force Awakens, is expected to be one of the major showstoppers of the convention.

Similarly, a planned panel for Batman vs Superman: Dawn of Justice, which will feature Ben Affleck (who is playing Batman), Henry Cavill (Superman) and Gal Gadot (Wonder Woman), is also expected to be one of the conventions big crowd pleasers.

Elsewhere in the vast San Diego Convention Centre, there are a raft of events, including some esoteric panels.

One, moderated by federal magistrate judge Paul Grewal, will address legal lessons from the Star Wars universe. Another will explore scientific accuracy in science fiction, with a panel featuring doctors, scientists and television program showrunners.

There is also the shamelessly camp, such as the launch of Sharknado 3: Oh Hell No, with the film's stars Ian Ziering, Tara Reid, Cassie Scerbo and David Hasselhoff, all in attendance.

One of preview night's biggest events was a launch for a Doctor Who tie-in to the Lego Dimensions game. Doctor Who stars Peter Capaldi, Michelle Gomez and Jenna Coleman attended, along with Doctor Who showrunner Steven Moffat.

The Doctor Who "pack" essentially allows players of the Lego Dimensions game to mash up pop culture universes, playing as Doctor Who characters alongside characters from Batman, The Lord of the Rings, Scooby Doo and The Lego Movie.

And for fans of nostalgia, Comic-Con does not disappoint. A reunion of the cast of Land of the Lost, including Wesley Eure, Kathy Coleman and Phil Paley, is planned. Another reunion, featuring the stars of Lost in Space - Bill Mumy (Will), Angela Cartwright (Penny), Mark Goddard (Don) and Marta Kristen (Judy), is also planned.

The convention runs until Sunday.