Vanessa Doofenshmirtz (2nd Dimension)

2nd Dimension Vanessa Doofenshmirtz is the daughter of 2nd Dimension Doofenshmirtz and 2nd Dimension Charlene, making a cameo appearance in Phineas and Ferb: Across the 2nd Dimension, and later as the secondary antagonist in Tales from the Resistance: Back to the 2nd Dimension. She is an alternate reality version of Vanessa Doofenshmirtz, but unlike her parents (who has a differentation in personality from their counterparts), she happens to retain the same personality and mannerisms as her original counterpart.

Like her original counterpart, she is voiced by Olivia Olson.

Across the 2nd Dimension
2nd Vanessa first appears in the TV film during the scene "Vanessa meets Doof", where she confronts her father (who is the dictator of the Tri-State Area in his dimension) for banishing her boyfriend Tony Marzulo for showing an interest towards her. She then notices another person standing next to her, asking who is he. Her father replies not to mind him, saying that it's just him from another dimension. 2nd Vanessa then storms off to her mother's place, and takes her father's blimp keys to get there. This scene was actually deleted from the finalized version, though it was later shown in the movie's DVD through the bonus features.

Tales from the Resistance
2nd Vanessa returns in the episode sequel, where she is seen staying at her mother's penthouse two months following her father's arrest for his crimes against humanity. She is also aware that her mother is just as evil as her father, since 2nd Charlene had turned several of O.W.C.A.'s agents into ruthless cyborgs, similar to how 2nd Doofenshmirtz turned 2nd Perry into Platyborg. As 2nd Vanessa leaves the scene, little did she know that the Resistance are coming by to the penthouse to take her mother into custody by bringing in her captive father along. While a freed 2nd Doofenshmirtz and 2nd Charlene attempt to battle against the kids, the Resistance freed the agents of their evil programming, and their leader, 2nd Dimension Candace Flynn, is about to take both 2nd Doofenshmirtz and 2nd Charlene into custody. However 2nd Vanessa arrives back to the scene, demanding everyone to stop fighting. She convinces 2nd Candace to let her have a moment with her evil parents. However, this was revealed to be a trick, as 2nd Vanessa (proving to be somewhat evil and intelligent like her parents) planned for Tony to drive both her family and Pandaborg in a hover car to escape from Resistance custody, much to 2nd Candace's anger. As the notorious Doofenshmirtz family escape, 2nd Vanessa introduces Tony to her parents, and 2nd Doofenshmirtz recognizes him as the boy he once banished earlier.