In the past PhD students have been successful in applying to external fellowships (those awarded by outside agencies including the NSF, DOG, etc). These fellowships can be a distinguishing factor on your CV when you enter the job market. Some fellowships that students have applied to include the following.
US Citizens: NSF GRFP, Ford, NDSEG, Hertz, Soros Fellowship for New Americans, GEM, SMART
Canadian Citizens: NSERC PGS-D, FRQSC B2Z
And the following fellowships which are more broadly eligible including: Google, Apple, Microsoft, OpenAI, Adobe, NVIDIA, IBM, Facebook, etc.