What is "holy mackerel"

interj. (context idiomatic humorous or euphemistic English) An expression of surprise.

Holy Mackerel may refer to:

• The Holy Mackerel, a figure seen in the chandelier of the Massachusetts State House Senate chamber
• The Holy Mackerel, a 1960s band featuring Paul Williams
• The Holy Mackerel, a 1990s band fronted by Les Claypool
• "Holy mackerel!", an exclamation originating from the American television show Amos 'n' Andy
• "Hey Hey Holy Mackerel", a 1969 Chicago Cubs fight song, written by Johnny Frigo
• The "Holy Mackerel", a humorous colloquialism for the fish-shaped Ichthys symbol