Assassin dream meaning is explained below using 10 different sources. Each interpretation is shown with its source.

Interpretation 1 — Gustavus Hindman Miller

If you are the one to receive the assassin’s blow, you will not surmount all your trials.

To see another, with the assassin standing over him with blood stains, portends that misfortune will come to the dreamer.

To see an assassin under any condition is a warning that losses may befall you through secret enemies.

Source: Ten Thousand Dream Interpretation • Author: Gustavus Hindman Miller

Interpretation 2 — DreamForth

To dream of being assassinated indicates a situation that has no optimism or chance of success and requires your instant consideration and effort.

To dream that you’ve witnessed an assassination means that you must pay closer attention to small details.

The seemingly inconsequential things are typically important.

Source: Dream Symbols and Analysis • Author: DreamForth

Interpretation 3 — Michael and Elizabeth Thiessen

If you are the one to be struck down by an assassin then you will not experience the realization of your goals.

To see someone else who has been killed, with the assassin still there, and blood spattered, shows some very bad luck to the dreamer, as he/she will be brought low by the underhandedness of an enemy.

Source: Encyclopedia of Dreams • Author: Michael and Elizabeth Thiessen

Interpretation 4 — Stephen Girard

To dream of an assassin is a warning not to be neglected. Shun all pretending friends, lend no money, be ever on your guard, and you may escape destruction, which ia planned for your ruin. 
Source: The Mystic Dream Book • Author: Stephen Girard

Interpretation 5 — Joan Seaman - Tom Philbin

If coming after the dreamer, he/she feels guilty over something.
Source: New American Dream Dictionary • Author: Joan Seaman - Tom Philbin

Interpretation 6 — Vincent Wienand

1. Spirit of death; Ps. 10:8,

2. False informant; 1 Kings 21:10

Source: Dream Dictionary The Biblical Model • Author: Vincent Wienand

Interpretation 7 — Raymond Buckland

Relief from unpleasant circumstances. Final gratification.
Source: Gypsy Dream Dictionary • Author: Raymond Buckland

Interpretation 8 — Margaret Hamilton

Fanatically motivated one who kills the spirit
Source: Dream Dictionary Unlimited • Author: Margaret Hamilton

Interpretation 9 — Stearn Robinson - Tom Corbett

See Crime and Killing.
Source: The Complete Guide to Interpreting Your Dreams • Author: Stearn Robinson - Tom Corbett

Interpretation 10 — Ibn Seerin

(See Thief)
Source: Islamic Dream Interpretation • Author: Ibn Seerin