The term "former colleague" refers to someone who used to work with you or be your workmate in the past, but is not currently working with you anymore. Full definition
Showing you're willing to submit your resume to public scrutiny, and the eyes of former colleagues, makes it more believable to recruiters and hiring managers than hiding it. (avidcareerist.com)
In addition to the core team, we got invaluable assistance from some of our friends and former colleagues in disciplines like animation, 3D modeling, and quality assurance. (supergiantgames.com)
You may have lost contact with former colleagues once you left a company. (careerattraction.com)