As per your request below I am providing you the list of some of these important government companies are:

1. Hindustan Machine Tools (Private) Limited

2. Bharat Electronics (Private) Limited

3. Bharat Heavy Electricals (Private) Limited

4. Hindustan Cable (Private) Limited

5. Hindustan Housing Factory (Private) Limited

6. Rashtriya Fertilizers and Chemicals (Private) Limited

7. Hindustan Antibiotics Limited

8. Indian Tourism Development Corporation

9. Indian Telephone Industries Limited

10. Indian Oil Corporation

11. Heavy Engineering Corporation

12. National Coal Development Corporation

13. Hindustan Insecticides (Private) Limited

14. Fertilizer Corporation of India Limited

15. Hindustan Shipyard Limited

16. Shipping Corporation of India Limited

17. Maruti Udyog Limited

List of Government banks in India:

State Bank and its associates

State Bank of India
State Bank of Patiala
State Bank of Mysore
State Bank of Travancore
State Bank of Bikaner and Jaipur
State Bank of Hyderabad

Nationalised banks

Allahabad Bank
Andhra Bank
Bank of Baroda
Bank of India
Bank of Maharashtra
Canara Bank
Central Bank of India
Corporation Bank
Dena Bank
Indian Bank
Indian Overseas Bank
Oriental Bank of Commerce
Punjab & Sind Bank
Punjab National Bank
Syndicate Bank
UCO Bank
Union Bank of India
United Bank of India
Vijaya Bank