Titan (rocket family)

Titan is US family of expendable rockets in use between years 1959 and 2005. Totally it was launched 368 rockets, including all the manned Gemini project flights. 

Titan was part of the US intercontinental ballistic missile, Titan was used to launch probes out to the Solar system.

The HGM-25A Titan I was the first rocket version used between years 1962 and 1965. It was first as a backup ICBM (intercontinental ballistic missile) in case that Atlas would be delayed. It was 2 stage rocket powered by RP-1 and liquid oxygen.  

The Titan II uses modified version of the LR-87 engine, that used combination of nitrogen tetroxide for its oxidizer and Aerozine 50 (50/50 mix of hydrazine and UDMH=unsymmetrical dimethylhydrazine) for its fuel instead of the liquid oxygen and RP-1 used in the Titan I. 
All together 12 Titan II Gemini launch vehicles were launched, including 2 unmanned tests and 10 manned flights with two-man crews. 

Launch of Gemini 11 on Titan GLV vs. Gemini 1 to 12 launch profiles

The Titan III was modified Titan II. The Titan IIIE version with high Centaur upper stage was used to launch both Voyager space probes and two Vikings missions to place two orbiter around Mars and two landers on the surface of Mars.

The Titan IV was stretched Titan III with solid rocket boosters on its sides. It also launched NASA-ESA Cassini/Huygens space probe to Saturn in 1997.