System:serviceaccounts

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 accounts
• system:, system:masters, system:controller:, system:anonymous, system:serviceaccount:, system:serviceaccounts:, system:bootstrappers, system:node, system:nodes, kubectl get clusterroles