Soundwave is one of the most recognizable characters from the original Transformers line due to his unique alternate mode, a microcassette recorder, and his distinctive, monotone, computerized voice.
Soundwave can detect and jam radio transmissions all across the energy spectrum, a talent that makes him naturally suited to his position as Decepticon Communications Officer. Additionally, he has a photographic memory thanks to the vast data storage capacity of the magnetic disks in his chest compartment, and he is armed with a shoulder-mounted radio wave sensor and hand-held concussion blaster. Soundwave is physically strong compared to most Transformers.
He transforms, shrinking as he does so, into an Earthly microcassette deck, and in the tape compartment, which becomes his chest in robot mode, he stores the Decepticon spy cassettes. Ravage, Laserbeak, Buzzsaw, Ratbat, Rumble, Frenzy, Slugfest, and Overkill are under his command in the original television series. Squawktalk, and Beastbox were the final two cassettes under Soundwave's control in the US toyline, but never appeared in animation.
Soundwave's cassettes are quick to serve and defend Soundwave in a crisis, and generally relate to him as servants or even pets. However, when his cassette Ratbat became leader of the Decepticons in the Marvel comics series, Soundwave shifted his trademark loyalty from Megatron to him. In the Dreamwave comics, Ratbat led the Ultracons faction, while Soundwave remained with the Decepticons led by Shockwave, although this was before Ratbat became a cassette.
In the IDW comics, Soundwave was in fact a personal assistant to the Senator, Ratbat, but his true loyalty lay with Megatron. When the time came for him and Starscream to massacre the Senate, he enslaved Ratbat with the smaller and weaker body of a cassette.