System:serviceaccount:

system:serviceaccount:

system:serviceaccount: (singular) is the prefix for service account usernames.
system:serviceaccounts: (plural) is the prefix for service account groups.

Related

• system:masters

See also

• Kubernetes service account, ServiceAccount:, kubectl get serviceaccounts, kubectl create serviceaccount, kubectl describe serviceaccount, kubernetes.io/service-account-token, Kubernetes users, Kubernetes groups, Kubernetes roles, ServiceAccountTokenNodeBinding