Name of S-Corp
Typically the name of a corporation must end with "Inc." "Corp", "Incorporated" or "Corporation". Most states permit additional designators (also called entity identifiers), such as "Co.", "Company", "Ltd." etc. however, each state has it's own restrictions, so make sure to check with the state first before choosing one of the less common ones.
"LLC" can only be used for limited liability companies, not corporations.