A number of catalysts with different characteristics were prepared using various techniques and used as the catalysts for the growth of carbon nanotubes (CNTs). They include dc sputter deposited Ni thin films, rf sputter deposited Ni-containing diamondlike carbon (Ni-DLC), and Co thin films deposited using a molecular beam epitaxy (MBE) technique. The growth of CNT from MBE-Co thin films was favored under a higher pressure, MW power, and/or methane concentration. For the Ni thin films, exhibiting different crystallinity, it appears that an optimal or largest diameter can be obtained under a lower pressure when an amorphous catalyst is used. Various amounts of carbon nanowires (CNWs) were observed, depending on the thickness or the crystallinity of the catalyst. The formation of CNW also depends on the pressure. Finally, the CNT diameter seems to increase with the nanoparticle size in the Ni-DLC. Furthermore, the yield tends to increase with the concentration of Ni nano-particles in the DLC.