The line includes non-transformable 3" and transformable 6" figures from a variety of Transformers lines—including Alternators, Beast Wars, Beast Machines, Cybertron, War Within, Generation 1 and Generation 2, Robots in Disguise and the 2007 film.
Transformable 6" Cybertron Heroes 
|Optimus Prime||2006 wave 1 (August)||The War Within - Re-released as a 2-pack with The War Within Megatron as a Toys R' Us Exclusive|
|Megatron||2006 wave 1 (August)||Generation 2 / G.I. Joe crossover|
|Thundercracker||2006 wave 2 (September )||The War Within|
|Jetfire||2006 wave 2 (September )||The War Within|
|Scourge||2006 wave 3 (October)||Generation 1|
|Optimal Optimus||2006 wave 3 (October)||Beast Wars|
|Rodimus Prime||2007 wave 1||Generation 1|
|Soundwave with Laserbeak||2007 wave 1||Generation 1|
|Optimus Prime||2007 wave 2||Robots in Disguise|
|The Fallen||2007 wave 2||The War Within|
|Cheetor||2007 wave 3||Beast Machines|
|Starscream||2007 wave 3||repaint of War Within Thundercracker|
|Ultra Magnus||2007 wave 4||Generation 1|
|Megatron||2007 wave 4||The War Within - Re-released as a 2-pack with The War Within Optimus Prime as a Toys R' Us Exclusive|
|Sunstorm||2007 wave 5 (May)||repaint of War Within Thundercracker|
|Ultra Magnus||2007 wave 5 (May)||repaint of War Within Optimus Prime|
|Menasor||N/A||repaint of Rodimus Prime; exclusive to 2007 Comic-Con International|
|Prowl||2008 wave 6 (Fall)||War Within; exclusive to Toys'R'Us fall 2008|
|Grimlock||2008 wave 6 (Fall)||The War Within; exclusive to Toys'R'Us fall 2008|
|Soundblaster with Ravage||Unknown||likely repaint of Soundwave; status unknown|
|Primal Prime||Unknown||likely repaint of Optimal Optimus; status unknown|
|Skywarp||N/A||repaint of War Within Thundercracker; exclusive to 2008 Comic-Con International|
|Thrust||N/A||repaint of War Within Thundercracker; Target store exclusive|
|Hot Zone||N/A||repaint of RID Optimus Prime; Target store exclusive|
|Optimus||N/A||repaint of The War Within Optimus Prime painted to resemble Optimus from Movie; Target store exclusive|
Non-transformable 3" Robot Masters 
|Megatron||1||Beast Wars original T-Rex|
|Optimus Prime||1||The War Within|
|Unicron||1||Generation 1 holding one of Cybertron's moons|
|Optimus Primal||3||Beast Wars original gorilla|
|Optimus Prime||4||Generation 1|
|Rodimus||6||Generation 1 Hot Rod|
|Thundercracker||6||repaint of Starscream|
|Optimus Prime||7||Generation 1 battle-damaged variant|
|Cliffjumper||8||repaint of Bumblebee|
|Sunstreaker||8||repaint of Sideswipe|
|Optimus Prime||N/A||2007 movie;
triple pack: robot, truck and protoform;
|Bumblebee||9||2007 movie ('74 Camero)|
|Optimus Prime||9||2007 movie|
|Nemesis Prime||?||repaint of War Within Optimus|
Pricing error 
When the first series of the 6" Titanium series figures was released in August 2006, Target stores initially sold them for their suggested retail price, but then shortly afterwards their computer systems started swapping the prices for the 6" and 3" figures. This resulted in the prices ringing up for 6" figures at one third their normal price, and the 3" figures ringing up at three times their normal price. After a few weeks the problem was fixed. The 3" figures soon returned to their original price, and also sported a sign saying they were "reduced".
Future releases 
A pamphlet included with The Fallen and Cheetor lists many new 3" Robot Masters. They include characters from the 2007 movie (Decepticon Brawl, Autobot Ratchet) as well as the following: War Within Megatron, Jetfire, Soundblaster, Skywarp, Silverstreak, Black Rodimus, Shockwave, Ultra Magnus, and Grimlock. It is unknown at this time if any of these new figures are repaints of existing molds. Apart from the movie characters, these have not seen a release yet.
The 6" line has been canceled and Grimlock and Prowl are said to be the final new molds released, though no schedule has been revealed. Molds for several unreleased figures were on display at the 2007 BotCon, and it's possible they may be released as part of other toy lines. They included Cosmos, Arcee, Shockwave, Silverstreak and War Within Bumblebee (along with a Cliffjumper head).
Grimlock and Prowl where released in August 2008 as ToysRUs exclusives. A Thundercracker redeco for Skywarp was released as a SDCC exclusive also available from Hasbrotoyshop.com.
Currently this is the end of the 6-inch (150 mm) Titanium line with all other prototypes being shelved by Hasbro.
During a panel discussion at BotCon 2009, a Hasbro employee stated that there are plans for more figures in the Titanium line to be released. 2009 saw the release of 3 redeco 6-inch (150 mm) figures as Target store exclusives, under the name label Transformers: Universe Titanium Series.