Other types and usages are:

Built-in Type Usage

• Opaque arbitrary user-defined data

• kubernetes.io/service-account-token ServiceAccount token

• kubernetes.io/dockercfg serialized ~/.dockercfg file

• kubernetes.io/dockerconfigjson serialized ~/.docker/config.json file

• kubernetes.io/basic-auth credentials for basic authentication

• kubernetes.io/ssh-auth credentials for SSH authentication

• kubernetes.io/tls data for a TLS client or server

• bootstrap.kubernetes.io/token bootstrap token data

Source: https://kubernetes.io/docs/concepts/configuration/secret/#secret-types