Mirza Asadullah Baig Khan (Urdu/Persian: مرزا اسد اللہ خان ), pen-name Ghalib (Urdu/Persian: غالب, ġhālib) and Asad (former pen-name)(27 December 1796 — 15 February 1869), was an all time great classical Urdu and Persian poet of the subcontinent. Most notably, he wrote several ghazals during his life, which have since been interpreted and sung in many different ways by different people. He is considered to be the most dominating poet of the Urdu language.

Life
Ghalib's closest rival was poet Zauq, tutor of Bahadur Shah Zafar II, the then emperor of India with his seat in Delhi. There are some amusing anecdotes of the competition between Ghalib and Zauq and exchange of jibes between them. However, there was mutual respect for each other's talent. Both also admired and acknowledged the supremacy of Meer Taqi Meer, a towering figure of Urdu Poetry of 18th century. Another poet Momin, whose ghazals had a distinctly lyrical flavor, was also a famous contemporary of Ghalib.

Contemporaries and disciples
Although Ghalib wrote in Persian as well, he is more famous for his ghazals written in Urdu. It is believed he wrote most of his very popular ghazals by the age of nineteen. His ghazals, unlike those of Meer Taqi Meer, contain highly Persianized Urdu, and are therefore not easily understood or appreciated by a vast majority of people without some extra effort. Before Ghalib, ghazal was primarily an expression of anguished love but he expressed philosophy, the travails of life and many such subjects, thus vastly expanding the scope of ghazal. This, together with his many masterpieces, will forever remain his paramount contribution to Urdu Poetry and Literature.
In keeping with the conventions of the classical ghazal, in most of Ghalib's verses, the identity and the gender of the beloved is indeterminate. The beloved could be a beautiful woman, or a beautiful boy, or even God. As the renowned critic/poet/writer Shamsur Rahman Faruqui explains, since the convention of having the "idea" of a lover or beloved instead of an actual lover/beloved freed the poet-protagonist-lover from the demands of "realism", love poetry in Urdu from the last quarter of the seventeenth century onwards consists mostly of "poems about love" and not "love poems" in the Western sense of the term. Ghalib's poetry is a fine illustration of this. Ghalib also excels in deeply introspective and philosophical verses.
The first complete English translation of Ghalib's love poems (ghazals) was written by Dr. Sarfaraz K. Niazi(http://www.ghalib.org) and published by Rupa & Co in India and Ferozsons in Pakistan. The title of this book is Love Sonnets of Ghalib and it contains complete roman transliteration, explication and an extensive lexicon.

His Letters
His original Takhallus (pen-name) was Asad, drawn from his given name, Asadullah Khan. At some point early in his poetic career he also decided to adopt the taKhallus 'Ghalib' (meaning all conquering, superior, most excellent).
Popular legend has it that he changed his nom de plume to 'Ghalib' when he came across this sher (couplet) by another poet who used the taKhallus 'Asad':
The legend says that upon hearing this couplet, Ghalib ruefully exclaimed, "whoever authored this couplet does indeed deserve the Lord's rahmat (mercy) (for having composed such a deplorable specimen of Urdu poetry). If I use the taKhallus Asad, then surely (people will mistake this couplet to be mine and) there will be much la'anat (curse) on me!" And, saying so, he changed his takhallus to 'Ghalib'.
However, this legend is little more than a figment of the legend-creator's imagination. Extensive research performed by commentators and scholars of Ghalib's works, notably Imtiaz Ali Arshi and Kalidas Gupta Raza, has succeeded in identifying the chronology of Ghalib's published work (sometimes down to the exact calendar day!). Although the taKhallus 'Asad' appears more infrequently in Ghalib's work than 'Ghalib', it appears that he did use both his noms de plume interchangeably throughout his career and did not seem to prefer either one over the other.
See note at Urdu poetry#Pen names

His Takhallus
Indian Cinema has paid a tribute to the legendary poet through a film (in sepia/black and white) named Mirza Ghalib (made in 1954) in which Bharat Bhushan plays Ghalib and Suraiya plays his courtesan lover, Chaudvin. The musical score of the film was composed by Ghulam Mohammed and his compositions of Ghalib's famous ghazals are likely to remain everlasting favorites.
Pakistan Cinema has also paid tribute to the legendary poet through another film also named Mirza Ghalib. The film was directed by M.M. Billoo Mehra and produced as well by M.M. Billoo Mehra for S.K. Pictures. The music was composed by Tassaduq Hussain. The film starred Pakistan film superstar Sudhir playing Ghalib and Madam Noor Jehan playing his courtesan lover, Chaudvin. The film was released on November 24, 1961 and reached average status at the box-office, however, the music remains memorable in Pakistan to this day.
Gulzar produced a TV serial titled Mirza Ghalib. It was telecast on DD National and was quite well-accepted and liked by viewers. Naseeruddin Shah played Ghalib in the serial. The ghazals were sung by Jagjit Singh and Chitra singh.
Pakistan government in 1969 commissioned Khaliq Ibrahim (died 2006) to make a documentary on Mirza Ghalib. The movie was completed in 1971-2, and is regarded as a masterpiece. It is said, that the movie--a docu-drama--was historically more correct than what the official Pakistan government point of view was. Thus, it was never released. Till this date, barring a few private viewing, the movie is lying with the Department of Films and Publication, Government of Pakistan. The movie was made on 16 mm format. Ghalib's role was played by actor Subhani Bayunus, who later played this role in many TV productions.
Various Theatre groups have staged various plays related to the life of Mirza Ghalib,have shown different life styles and the way he used to live his life.One of the leading theatre group in New Delhi Pierrot's Troupe staged a play named "GHALIB IN NEW DELHI" where it was shown if Ghalib returns back to his beloved Dilli.and what all changes will he see here.It is a comedy directed by Dr.M.Sayed Alam.

Deewan-E-Ghalib Online

Urdu poetry
List of Urdu language poets