Energy weapons were any device that intended to use directed energy in a destructive manner.
Anti-personnel energy weapons
An energy weapon could be a handheld weapon that fired energy rather than a projectile of some sort.
The Chancellery Guard on Gallifrey used a weapon called a staser. According to one account, staser fire prevented regeneration. (TV: Arc of Infinity) However, the Twelfth Doctor shot the General once with the sidearm of the President's personal security, triggering the General's regeneration. (TV: Hell Bent)
Jack Harkness carried a Compact laser deluxe, which was able to defeat the androids Trine-E and Zu-Zana when they tried to kill him. Shortly afterwards, Jack improvised an energy weapon out of the defabricator. (TV: Bad Wolf)
Several species and individuals specifically identified their energy weapons as ray guns. The Moroks, (TV: The Space Museum) the Cat-People, (PROSE: Invasion of the Cat-People) and the Scorchies used ray guns themselves. (AUDIO: The Scorchies) The Monstrons armed their Engibrain soldiers with ray guns. (COMIC: The Menace of the Monstrons)
Some merely referred to themselves (or others as possessing "ray guns") as the Daleks did in reference to their own gunsticks (TV: The Daleks' Master Plan) and Jamie McCrimmon and the Second Doctor did when describing the Chameleons' weaponry. (TV: The Faceless Ones)
The First Doctor and Ian Chesterton constructed a ray gun which Ian used to destroy a Dalek. (COMIC: The Defeat of the Daleks) He later used a different ray gun on an Aquafein which had grabbed Barbara Wright. (COMIC: Escape from the Aquafien)
On one occasion the Second Doctor invented a ray gun which he tested on an Earth-like planet. When the Master of Spiders attacked them, he used the ray gun to kill one spider and to destroy the Master's mechanical spider. (COMIC: Master of Spiders) He later used the ray gun on a giant squid which attacked him on Nook. (COMIC: Peril at 60 Fathoms)
Large-scale energy weapons
The Daleks used ship-mounted energy weapons during their invasions of Earth in the 21st (TV: The Stolen Earth) and 22nd century. (TV: The Dalek Invasion of Earth) They also utilised Special Weapons Daleks that were equipped with an enormous energy cannon capable of vaporising several other Daleks in a single shot. (TV: Remembrance of the Daleks)
Other ship-mounted weapons such as a Jathaa sunglider weapon, deployed by the Torchwood Institute in 2007 during the Sycorax's appearance over London on Christmas day were also capable of massive destruction, destroying the aforementioned Sycorax and their ship. (TV: The Christmas Invasion)