Propellants

A hypergolic blend of UDMH and hydrazine with N2O4 oxidizer, used by the Titan family and various upper stages during the 20th century.

Liquid hydrogen burned with liquid oxygen — the highest-performing chemical propellant by specific impulse, but low-density and deeply cryogenic. Used by the RS-25, RL10, Vulcain, and LE-7/LE-9.

Liquid methane burned with liquid oxygen. A modern choice balancing performance, density, and reusability (clean-burning, in-situ producible on Mars); used by Raptor, BE-4, and Vulcain-class successors.

A storable hypergolic combination used in upper stages and orbital-maneuvering systems where reliable restart matters, such as the Ariane 5 storable upper stage.

A refined-kerosene fuel burned with liquid oxygen. Dense and room-temperature-storable fuel with a cryogenic oxidizer; the workhorse first-stage combination from the Saturn V's F-1 to SpaceX's Merlin.

A cast solid propellant of ammonium-perchlorate oxidizer, aluminium fuel, and a rubber binder. High thrust and simplicity, but not throttleable or shut-down-able once lit; used in the Shuttle/SLS boosters, Vega, and many strap-on boosters.

A storable hypergolic combination that ignites on contact without an igniter. Long the mainstay of the Proton and early Long March vehicles; toxic and being phased out for new designs.