In what are compilations of all released DLC and post-launch updates for Empire: Total War, Napoleon: Total War and Medieval II: Total War. The good news is that for everyone who owns any of the above your current version will be automatically updated to the Definitive Edition - which, again, grants access to all DLC and post-launch updates.

About Total War: EMPIRE
Control the land and command the seas. Total War: EMPIRE immerses you in the Age of Enlightenment, a time of political upheaval, military advancements, and endless possibilities. BAFTA winning EMPIRE came out in 2009 to universal acclaim, scoring a 90 on Metacritic and huge scores of 95% from the likes of IGN and Game Informer.
Includes: Elite Units of the East; Elite Units of America; The Warpath Campaign.
https://store.steampowered.com/app/10500/Empire_Total_War/

About Total War: MEDIEVAL II
Expand your reign in Total War: MEDIEVAL II. Make your mark in massive battles featuring up to 10,000 bloodthirsty troops throughout the most turbulent era in Western history. MEDIEVAL II came out in 2006 and was the 2007 winner of the Satellite Award for outstanding strategy game. It was also nominated for several awards, including BAFTA's Games Award for both the main game and DLC.
Includes: Medieval II: Total War Kingdoms
https://store.steampowered.com/app/4700/Medieval_II_Total_War/

About Total War: NAPOLEON
From Italy to Waterloo, Total War: NAPOLEON covers two decades of relentless battles as the story of an extraordinary military career unfolds. Its score was critically claimed, receiving the IVOR Novello Award for Best Original Video Game Score in 2011.
Includes: Coalition Battle Pack; The Peninsular Campaign; Imperial Eagle Pack; Heroes of the Napoleonic Wars
https://store.steampowered.com/app/34030/Napoleon_Total_War/

A nice little Christmas bonus from Creative Assembly for long-time fans and supporters of the Total War series. And for those that don't any of the above, with Steam's new Australian pricing they're available for AUD $35.99 each.