The definition of Promoter is not given in Companies Act, 1956 so we take the help of other laws for defining the term promoter".
For this, you can take the help of Regulation 2(za) of SEBI(ICDR) Regulation 2009:
“promoter” includes: (i) the person or persons who are in control of the issuer; (ii) the person or persons who are instrumental in the formulation of a plan or programme pursuant to which specified securities are offered to public; (iii) the person or persons named in the offer document as promoters: Provided that a director or officer of the issuer or a person, if acting as such merely in his professional capacity, shall not be deemed as a promoter:
Provided further that a financial institution, scheduled bank, foreign institutional investor and mutual fund shall not be deemed to be a promoter merely by virtue of the fact that ten per cent. or more of the equity share capital of the issuer is held by such person;
Provided further that such financial institution, scheduled bank and foreign institutional investor shall be treated as promoter for the subsidiaries or companies promoted by them or for the mutual fund sponsored by them;