The author of the Yoga Sutras - the most famous Yoga text
The commentator on Panini's grammar - the author of Mahabhashya
But was he a single man or many men?
This is something I read in Edwin Bryant's work
This is evident from the shloka that features in the great Malwa king Bhoja's commentary on the Yoga Sutras -
मलं शरीरस्य च वैद्यकेन॥
योऽपाकरोत्तं प्रवरं मुनीनां।
पतञ्जलिं प्राञ्जलिरानतोऽस्मि॥
आबहु पुरुषाकारं।
शङ्खचक्रासि धारिणं॥
सहस्र शीरसं श्वेतं।
प्रनमामि पतञ्जलिम्॥
ॐ शान्तिः शान्तिः शान्तिः ॐ॥
At that point I didnt know this came from Bhoja's work - the 11th century king
"Yoga for bringing quietness of mind;
Grammar for eliciting effectiveness of speech
And the healing arts for removing the ailments of the body
That most illustrious of sages who bestowed all these things
Patañjali to whom I make reverential obeisance."
Bearing the conch, the discus and the sword
Adorned with the cobra of one thousand heads—
I bow down before Patañjali.
Om shanti shanti shanti"
We are not sure if Bhoja composed this or he is quoting someone. But clearly in this invocatory verse used by Bhoja, obeisance is paid to Patanjali who has three great distinctions -
The master of Yoga
The elucidator of Grammar
The Ayurvedic expert
And this verse is unequivocal in associating all three with the same figure
So Patanjali suddenly becomes this quasi-divine sage :)
But clearly this was a great man who captured the imagination of many generations of learned Indians
Perhaps there were more than 1 Patanjali. But tradition chose to treat them as one. Either through historical memory or conscious conflation