Batman LEGO themed sets are one of the more unique themes released by LEGO as the different Batman LEGO sets can be so different from each other. LEGO has released Batman themed sets based on everything from the original Batman movie in 1989 to the newer Dark Knight film. This results in different style LEGO Batmobiles and other vehicles.
Batman LEGO mini figures are very collectible. The LEGO Group did a fantastic job with the fan crossover from Batman Comics to LEGO collecting.
The minifigs included with Batman LEGO Sets can be extremely difficult to find if the set it comes in is discontinued. A good example of that is the extremely difficult to find Batman Arkham Asylum Lego Set 7785. This is a great set because of it's size and because of all the minifigs it has. The Asylum set has seven LEGO mini figures, Batman, Nightwing, Scarecrow, The Riddler, Poison Ivy, and 2 Asylum Gaurds.