Some examples of biologically important molecular motors:
* Cytoskeletal motors
** Myosins are responsible for muscle contraction, intracellular cargo transport, and producing cellular tension. 
** Kinesin moves cargo inside cells away from the nucleus along microtubules, in anterograde transport.
** Dynein produces the axonemal beating of cilia and flagella and also transports cargo along microtubules towards the cell nucleus, in retrograde transport.
* Polymerisation motors
** Actin polymerization generates forces and can be used for propulsion. ATP is used.
** Microtubule polymerization using GTP.
** Dynamin is responsible for the separation of clathrin buds from the plasma membrane. GTP is used.
*Rotary motors:
**FF-ATP synthase family of proteins convert the chemical energy in ATP to the electrochemical potential energy of a proton gradient across a membrane or the other way around. The catalysis of the chemical reaction and the movement of protons are coupled to each other via the mechanical rotation of parts of the complex. This is involved in ATP synthesis in the mitochondria and chloroplasts as well as in pumping of protons across the vacuolar membrane.
** The bacterial flagellum responsible for the swimming and tumbling of E. coli and other bacteria acts as a rigid propeller that is powered by a rotary motor. This motor is driven by the flow of protons across a membrane, possibly using a similar mechanism to that found in the F motor in ATP synthase.
* Nucleic acid motors:
** RNA polymerase transcribes RNA from a DNA template.
** DNA polymerase turns single-stranded DNA into double-stranded DNA.
** Helicases separate double strands of nucleic acids prior to transcription or replication. ATP is used.
** Topoisomerases reduce supercoiling of DNA in the cell. ATP is used.
** RSC and SWI/SNF complexes remodel chromatin in eukaryotic cells. ATP is used.
** SMC proteins responsible for chromosome condensation in eukaryotic cells.
** Viral DNA packaging motors inject viral genomic DNA into capsids as part of their replication cycle, packing it very tightly. Several models have been put forward to explain how the protein generates the force required to drive the DNA into the capsid. An alternative proposal is that, in contrast with all other biological motors, the force is not generated directly by the protein, but by the DNA itself. In this model, ATP hydrolysis is used to drive protein conformational changes that alternatively dehydrate and rehydrate the DNA, cyclically driving it from B-DNA to A-DNA and back again. A-DNA is 23% shorter than B-DNA, and the DNA shrink/expand cycle is coupled to a protein-DNA grip/release cycle to generate the forward motion that propels DNA into the capsid.
* Enzymatic motors: The enzymes below have been shown to diffuse faster in the presence of their catalytic substrates, known as enhanced diffusion. They also have been shown to move directionally in a gradient of their substrates, known as chemotaxis. Their mechanisms of diffusion and chemotaxis are still debated. Possible mechanisms include solutal buoyancy, phoresis or conformational changes leading to change in effective diffusivity and kinetic asymmetry.
**Catalase
**Urease
**Aldolase
**Hexokinase
**Phosphoglucose isomerase
**Phosphofructokinase
**Glucose Oxidase 
A recent study has also shown that certain enzymes, such as Hexokinase and Glucose Oxidase, are aggregating or fragmenting during catalysis. This changes their hydrodynamic size that can affect enhanced diffusion measurements. 
*Synthetic molecular motors have been created by chemists that yield rotation, possibly generating torque.