What is Shareholder?

Legal Definition
A shareholder or stockholder is an individual or institution (including a corporation) that legally owns a share of stock in a public or private corporation. Shareholders may be referred to as members of a corporation. Legally, a person is not a shareholder in a corporation until his or her name and other details are entered in the corporation's register of members.

Shareholders of a corporation are legally separate from the corporation itself. They are generally not liable for the debts of the corporation; and the shareholders' liability for company debts are said to be limited to the unpaid share price, unless if a shareholder has offered guarantees. The assets of the corporation are not assets of the shareholders. The only entitlement of shareholders is to a dividend declared and paid in accordance with the applicable laws and rules of the corporation, and to a share of the capital of the corporation on winding up.
-- Wikipedia
Legal Definition
In the strict sense of the term, a "shareholder" is a person who has agreed to become a member of a corporation or company, and with respect to whom all the required formalities have been gone through; e. g., signing of deed of settlement, registration or the like. A shareholder by estoppel is a person who has acted and been treated as a shareholder, and consequently has the same liabilities as if he were an ordinary shareholder. Lindl. Partn. 130. See Beni v. Essex Sav. Bank, 67 Fed. 816, 15 G. C. A. 128; State v. Mitchell, 104 Tenn. 336, 58 S. W. 365.
-- Black's Law Dictionary
Legal Definition
A person who owns stock in a corporation.
See also
Legal Definition
-- Ballentine's Law Dictionary