Among his most important early roles were Cuchulainn in W. B. Yeats's On Baile Strand (1966), and as Estragon in a seminal production of Samuel Beckett's Waiting for Godot, partnering with Peter O'Toole as Vladimir (1969).
His career included parts in many plays from the Irish literary canon, including Tarry Flynn, The Shaughran, and the Gate Theatre's highly acclaimed production of Seán O'Casey's classic Juno and the Paycock in the 1980s (McCann played the "Paycock" (Captain Boyle) opposite Geraldine Plunkett as Juno and John Kavanagh as Joxer Daly) as well as a subsequent production of O'Casey's The Plough and the Stars.
He gave a landmark performance as Frank Hardy, the title character, in Faith Healer in 1980 (a role he reprised in 1994), continuing his relationship with Friel through productions of Translations (1988) and Wonderful Tennessee (1993).
More significant roles included the title character's father Shamie in Cal and one of the feuding brothers in Thaddeus O'Sullivan's December Bride (1990–1994).
Significant late roles included Bernardo Bertolucci's Stealing Beauty (1996) and in John Turturro's Illuminata (released in 1999, after McCann's death).
[3] Remembering McCann on the 25th anniversary of his death, Gerald Smyth wrote, "In the melancholy of that life-worn voice could be heard the cadences of a lyric heart.