New Delhi, Oct 11 (IANS) President Ram Nath Kovind, Prime Minister Narendra Modi and a string of Bollywood celebrities like Lata Mangeshkar, Aamir Khan, Ranveer Singh and Rishi Kapoor on Wednesday wished megastar Amitabh Bachchan good health and happiness on his 75th birthday. "Birthday wishes to Amitabh Bachchan, film icon as well as unstinting advocate of social causes and nation building missions," President Kovind tweeted. Modi wrote: "Happy birthday Amitabh Bachchan! India is proud of his cinematic brilliance and support to many social causes. I pray for his long and healthy life," Modi tweeted. Labels like "biggest superstar", "super hero of Indian cinema" and an "inspiration" have been used for Amitabh, whose career spans over four decades in the Hindi film industry. Having started his career with "Saat Hindustani" in 1969, Big B has given Indian cinema hits like "Deewar", "Sholay", "Agneepath","Paa", "Black" and "Piku". Here's what his colleagues, friends and juniors tweeted: Lata Mangeshkar: Namaskar. The person who has entertained the entire universe with his acting talent, I wish that superstar Amitabh Bachchan on his birthday. Aamir Khan: To the biggest superstar India has ever seen. Many many happy returns of the day! May you always have good health, happiness, joy, excitement, adventure and fulfilment. May all your dreams come true, and may your list of dreams never end. Love, your biggest fan. Aamir. Ranveer Singh: Happy Amitabh Bachchan Day to all! Greatest of all time. Rishi Kapoor: We have done some interesting work together. Now await '102 Not Out'. This time Comic Drama. Rakesh Roshan: Amitji Happy Birthday. Farah Khan: He possesses the magic or the magic possesses him! Amitabh Bachchan... Happy birthday thank you for being you! Rajkummar Rao: Sir, can't thank you enough for all this love and support and Happy Birthday, my most favourite actor and person. Thank you for teaching me so many things in life. Subhash Ghai: Our heartiest wishes to Amitabh of Indian cinema - an institution of a great kalakar karmyogi n yodhha Amitabh Bachchan. Ranvir Shorey: Amitabh Bachchan, Happy Birthday, sir! 75, and still number 1! Abhishek Kapoor: Happy birthday Amitabh Bachchan sir. Have a great day and thank u for being u and the inspiration?? Rahul Dholakia: Happy 75th Sir Amitabh Bachchan - love and wishes. Papon Angaraag: Happy birthday to the super hero of Indian cinema and one of the most amazing person I've ever met! Amitabh Bachchan ..Happy birthday sir! Maniesh Paul: Wish u a very very happy birthday Amitabh Bachchan sir..stay blessed and always be the driving force for all of us that you are...love you sir. Esha Deol: Happy birthday to the one and only Amitji wishing you good health and happiness always.