Laser

A laser is a concentrated beam of energy. They are often used in offensive weaponry.

History
The X-Men had lasers in the Danger Room.

Alistair Smythe used lasers in his Spider-Slayers.

Stark Enterprises used lasers in its defensive weaponry.

Iron Man uses a kind of laser dubbed a Repulsor Beam.

The Avengers Mansion has numerous laser weapons for defense.

Background
Lasers and other types of energy weapons were used in place of more realistic ballistic weapons due to various censorship issues.