Friedrich Zander (August 23, 1887 - March 28, 1933), often referred to as Fridrikh Tsander (transliterated from the Russian version of his name: Фридрих Артурович Цандер) or Fridrihs Canders (the Latvian version of it) was a Soviet pioneer of rocketry and spaceflight. He designed the first liquid-fuelled rocket to be launched in the Soviet Union and made many important theoretical contributions to the road to space.

Zander was born in Riga into an ethnically German family. His father Artur Konstantinovich was a doctor. Friedrich trained as an engineer and became fascinated by the ideas and work of Konstantin Tsiolkovsky. In particular, he became passionate about the exploration of Mars, adopting "towards Mars!" as a personal slogan, and made precise calculations of the trajectory required to get there. In 1908, he published his first work considering the problems of interplanetary travel in which he addressed issues such as life support and became the first to suggest growing plants in greenhouses aboard a spacecraft. In 1911, he published plans for a spacecraft built using combustible alloys in its structure that would take off like a conventional aircraft and then burn its wings for fuel as it reached the upper atmosphere and no longer needed them.

1924 was a particularly active year for Zander. Together with Yuri Kondratyuk and his mentor Tsiolokovsky, he founded the Society for Studies of Interplanetary Travel. In an early publication, they would be the first to suggest using the Earth's atmosphere as a way of braking a re-entering spacecraft. The same year, Zander lodged a patent in Moscow for a winged rocket that he believed would be suitable for interplanetary flight, and in October gave a lecture to the Moscow Institute on the possibility of reaching Mars by rocket. During questioning after the lecture, he summarised the importance of reaching this planet in particular: "because it has an atmosphere and the capacity to support life. Mars is also known as 'the red star' and this is the emblem of our grand Soviet army."

Around this time, Zander became the first to suggest the solar sail as a means of spacecraft propulsion.

In 1930 the Soviet government assigned two groups with the making and testing of rocket propulsion with liquid-fuel, one led by Zander and the other by Glushko.

In 1931, Zander was a founding member of GIRD (Group for the Investigation of Reaction Propulsion) (Группа изучения реактивного движения (ГИРД)) in Moscow. The group set about attempting to construct liquid-fuelled rockets, and it was its tenth attempt (the GIRD-X) that finally flew successfully on November 25, 1933. Zander had designed the rocket, but did not live to see it fly, having died earlier that year in Kislovodsk.

A crater on the Moon is named after him, and the Latvian Academy of Sciences awards a physics and mathematics prize in his honour.