Rape

Rape is the criminal act of forcibly having a sexual act with a person without their consent.

History
The ancestral Native American tribe to which Chakotay belonged at one time suffered frequent rape by "white conquerors". One of these rapes produced Ce Acatl, a great leader of their tribe. 

An evil transporter duplicate of Captain Kirk attempted to rape Janice Rand. 

In 2267, during Festival on the planet Beta III, when the inhabitants would lose their inhibitions to violence, rape occurred openly in the streets. Once the clock struck red hour, Kirk and the landing party from the USS Enterprise (NCC-1701) immediately witnessed men chasing after women. First, they saw a man grab a resistant woman across the street from them, and shortly afterward Bilar was seen dragging Tula away by her shoulder or hair. While running to seek shelter from the chaos, the landing party passed a man with white sleeves who was carrying a struggling woman over his shoulder. Shortly afterward, from the safety of a second floor window, Kirk saw the image of a man assaulting a woman in silhouette, and heard the screams of other women. Later, when festival was complete, Reger consoled a screaming, emotionally distraught Tula who had returned from Festival heavily traumatized by her experience with Bilar. 

Lars attempted to rape Uhura. 

In 2268, Ensign Pavel Chekov attempted to rape Klingon Science Officer Mara while under the influence of a non-corporeal lifeform that feeds on hatred. 

Rape gangs were a threat on Turkana IV. 

Manua Apgar accused Riker of attempted rape. 

A woman whom Kenneth Dalby fell in love with was raped and killed by three Cardassians, which motivated him to join the Maquis. 

Rape was rife during the Cardassian Occupation of Bajor, especially in the Gallitep labor camp, where women were raped in front of their children. 

Kira Nerys once described the Occupation in general to Silaran Prin by saying "For fifty years, you raped our planet." 

The Vori accused the Kradin of rape. 

When the Kazon captured Voyager, Maje Culluh said to Chakotay that "A man who would violate a woman under his own command doesn't deserve a son."

Background information
Shinzon's telepathic interaction with Troi through his Viceroy in was presented in the context of rape, similar to Troi's experience of telepathic memory invasion with the Ullian Jev in. Troi also experienced something akin to rape in where she was impregnated against her will in her sleep.

In DVD commentary, executive producer Rick Berman referred to Picard's transformation into Locutus of Borg as rape.

The taking of the Dax symbiont from Jadzia Dax by the Trill Verad in was presented in terms similar to rape.

Seven of Nine's recount of her "violation" by Kovin in was also presented in terms similar to rape.

Tucker's impregnation in can be considered rape, as he was deceived by Ah'len, the Xyrillian engineer into believing that their form of reproduction was simply a "game" he was being invited to play.

T'Pol's forced mind meld with Tolaris in is described in rape-like terms, particularly when T'Pol contracts a psionic illness as a result in.

Some legal definitions of rape include sex under false pretenses, such as Dukat's having sex with Winn Adami while pretending to be a Bajoran in. This concept is not universally recognized, and was not mentioned in the episode. Please see Wikipedia's article on Rape, linked below, for more information about how the term is defined.

Apocrypha
In the Star Trek: Deep Space Nine - Millennium novel Inferno,, a Bajoran Starfleet commander, experienced a Pah-wraith induced hell where, during the Occupation of Bajor, she was tortured and raped by the Cardassians for days before being killed, and then forced to "relive" those events again and again.