Austrian Beer was never subject to the Reinheitsgebot and has arguably had a chance to be more innovative and diverse than its Germanic neighbours, although still predominantly using bottom fermentation method. As a result Austrians consume over 100L of beer per person per annum and key brands include Stiegl, Eggen and Ottakringer.
The quintessential Austrian beer really should be Vienna lager, named for its place of creation, however sadly it has fallen out of fashion in its homeland, possibly due to the widespread popularity of Austrian Marzen.
Austrian Marzen - Traditionally brewed in March to use up the remainder of last harvest's malt and hops before brewing stopped for the summer months, Austrian Marzen is light in both colour and body, barely hopped with a malty character which is a touch sweeter than the German Marzen. Practically every Austrian brewery produces a Marzen, a popular brand being Eggenberg Classic Marzen.
Spezial - Spezial is a stronger style of pale lager, full-bodied and fairly hoppy, with an ABV of at least 5.5%. Look out for Stiegl Spezial for a good example of this style.
Zwickel - The term Zwickel refers to any beer that is left unfiltered and unpasteurised. Similar to Kellerbier, it's more frequently found on draught, although brands such as Gosser and Stiegl do produce bottled versions.