Ironic is the use of words to express something other than and especially the opposite of the literal meaning.
It is something characterized by irony.
Irony is a contradiction or incongruity between apperance or expectation and reality.
The word "irony" is among the most commonly misused (and misunderstood) words in the English language. Most people think that irony means a juxtaposition of opposites, as in: it was ironic that the fire station burned down. While this sentence has some element of irony in it, it is not really ironic, and does not portray the full and correct meaning of the word irony. True irony involves some form of deceit, or hypocrisy, be it intentional or accidental.
Something that is iconic is characteristic of an icon — an image, emblem, idol, or hero.
The adjective modifying the noun icon. In today’s parlance an icon is a super celebrity - not just a TV personality, or film star, but someone universally revered and regarded. For example, If someone is regarded as portraying the definitive role of, let us say Sherlock Holmes.