An incorporator is the person in charge of setting up a corporation and registering it with the state. They are responsible for filing the paperwork and signing the articles of incorporation. Each state has different laws about the incorporator, this article will take Delaware state as an example.

An incorporator is responsible for setting up a corporation. This role is primarily executed before the business is formed, with the incorporator taking key steps to ensure that the corporation is eventually recognized legally. The incorporator must sign the corporation's certificate of incorporation before filing with the state in which the corporation is registered.

According to the Delaware Code Title 8 Chapter 1 § 103, the certificate of incorporation, and any other instrument to be filed before the election of the initial board of directors if the initial directors were not named in the certificate of incorporation, shall be signed by the incorporator or incorporators (or, in the case of any such other instrument, such incorporator’s or incorporators’ successors and assigns). If any incorporator is not available then any such other instrument may be signed, with the same effect as if such incorporator had signed it, by any person for whom or on whose behalf such incorporator, in executing the certificate of incorporation, was acting directly or indirectly as employee or agent, provided that such other instrument shall state that such incorporator is not available and the reason therefor, that such incorporator in executing the certificate of incorporation was acting directly or indirectly as employee or agent for or on behalf of such person, and that such person’s signature on such instrument is otherwise authorized and not wrongful.

According to the Delaware Code Title 8 Chapter 1 § 107, if the persons who are to serve as directors until the first annual meeting of stockholders have not been named in the certificate of incorporation, the incorporator or incorporators, until the directors are elected, shall manage the affairs of the corporation and may do whatever is necessary and proper to perfect the organization of the corporation, including the adoption of the original bylaws of the corporation and the election of directors.

Delaware Code does not specify who can act as the incorporator. Generally, an incorporator must be 18 years old. The incorporator may be an attorney or other person hired expressly to serve as incorporator. Or, they may be a shareholder, a member of the board of directors, or an officer such as president, treasurer, or secretary.

Because this person is signing legal documents on behalf of the corporation, they should have the authority to act on behalf of the corporation. The incorporator can also act as the registered agent once the incorporation is complete.

According to the Delaware Code Title 6 Subtitle II. The certificate of formation for a limited liability company (LLC) can be signed by the authorized person instead of incorporator. An authorized person can be 1 or more person who performs the same functions as an incorporator. The authorized person may sign and file the articles of organization (similar to certificate of incorporation) and sign the operating agreement.

Reference：
https://www.thebalancesmb.com/what-is-an-incorporator-or-organizer-of-a-business-398297
https://delcode.delaware.gov/title8/c001/sc01/