Anna Valerious is the love interest of Van Helsing. Her mission needs to kill Dracula once and for all, following in her ancestor's footsteps who dedicated their lives in attempting to do so. She is the last heir to the royal bloodline of House Valerious and is therefore attacked several times. She proves herself to be formidable in her own right alongside Van Helsing. Throughout the movie she with Van Helsing kill Dracula's brides and succeed in ending Dracula's tyranny.

In order to kill Dracula, Van Helsing infected himself with lycanthropy to become werewolf. As previously seen in the movie with Prince Velkan, werewolves have a period of time in which they can be cured of the disease. Van Helsing rips Dracula's throat out just before he fully succumbs to the curse, in an effort to save him from remaining as a werewolf, Princess Anna rushes to him to inject him with the cure. Van Helsing, whilst feral, does not recognise Princess Anna and therefore jumps at her in attack. Anna is killed when the shock of the impact breaks her neck, much to Van Helsing's remorse.

Meeting Van Helsing

Van Helsing comes to Transylvania under orders to help Princess Anna kill Count Dracula whilst simultaneously seeking answers about his mysterious past. She meets him in a village in which she coldly orders Van Helsing to identify and disarm himself which he refuses before they are attacked by the brides Aleera, Verona, and Marishka. During the attack, Anna gets captured several times only to be saved by Van Helsing. While he deals with Marishka, she is cornered by Aleera and Verona. She avoids being bitten when they sense Marishka die, and the brides wail in agony and leave in a hurry of grief. Anna instantly recognizes him as Van Helsing because his controversial, 'criminal' history has preceded him.

Reuniting with Velkan

Once returning to her family's mansion, she wastes no time rearming herself. She prepares to locate and kill Dracula while exchanging information with Van Helsing and Carl about what her family knew. She was prevented from leaving after Helsing rendered her unconscious with a spray. While heading to confront Van Helsing for preventing her from going after Dracula, she sensed that something or someone was following her. The intruder is none other than her brother Velkan. Sometime before Van Helsing arrived, she and Velkan captured and attempted to kill a werewolf Dracula sent to eliminate them. Though Velkan saved Anna by shooting a silver bullet, he was knocked off a cliff by the werewolf and bitten in the process. Having presumed her brother dead, Anna is relieved to see her brother alive. Velkan exclaims he has no time and attempts to tell her that Dracula has a cure yet at that very moment, he transforms into a werewolf, devastating Anna in the process. Van Helsing comes to save Anna and Velkan escapes. Anna overhears Carl giving Van Helsing silver bullets and proceeds to stop him from killing the only family she had left. She saves her brother's life, but Van Helsing disapproves of her actions since Velkan is a threat and cannot be saved. Anna nonetheless convinces Van Helsing to help her find Velkan.

Castle Frankenstein

The trail leads to Castle Frankenstein which according to Anna, was abandoned after the owner Victor Frankenstein was killed a year prior. She mentioned her father disappeared around the same time. While exploring the castle, they discover strange pods which Van Helsing realizes contain the offspring of Dracula and his brides. She goes into a room in the upper tower where her brother is a test subject in an experiment. She intervenes to save her brother but at that moment, he transforms into a werewolf. She is saved by Van Helsing who escaped after having a strange conversation with Dracula. As they were escaping the castle by using a zip line, Velkan jumps onto the line only to snap the cable under his weight. Van Helsing and Anna swing into a forest while the Wolf Man falls into the river, but survives. While heading to a burned down windmill, Anna berates Van Helsing for using a silver stake and a crucifix on Dracula since her family had already tried using different methods to kill the vampire with no success. She apologizing for wasting time trying to save her brother. They share a moment by drinking absinthe but unexpectedly fall into an underground cave when the floor gives way underneath them.

Escaping

While inside the cave they encounter the Frankenstein Monster whom they capture and Anna attempts to kill, but Van Helsing intervenes. The Monster reveals that Dracula plans to bring his children to life mentioning the previously failed experiment and begged to be killed because his "father" Victor Frankenstein created the Monster under Dracula's orders not knowing his "son" was the key to bring Dracula's offspring to life. Unfortunately the three are seen by the Wolf Man. They then try to take the Monster to Rome for protection using Transylvanian horses, the only creatures capable of outrunning werewolves. The brides attack but Van Helsing, Anna, and Carl prepared a strategy ahead. Using two carriages, Van Helsing rides a decoy loaded with stakes while Anna and Carl were in the other carriage with the Monster. They succeed in killing Verona but are interrupted by the Wolf Man. The three barely jump out of the carriage before it crashes. Later in the morning, Anna encounters a wounded Velkan who is dying from a gunshot wound inflicted by Van Helsing. They share a tender moment before he dies. Out of grief, she attacks Van Helsing, discovering to her horror that he was bitten by her brother and unexpectedly gets knocked unconcious and kidnapped by Aleera.