Zoey Pierson is one of Ted Mosby's girlfriends in How I Met Your Mother.
Zoey is a social activist. She meets Ted outside a dilapidated building called The Arcadian which she believes should be preserved. Ted just so happens to be in charge of the new building, but he doesn't tell her that as he's attracted to her. Zoey finds out and tries to make Ted's life miserable. Ted still like Zoey despite this so he tries to come to a compromise, but as soon as he finds out that Zoey is married he completely turns on her.
When Ted sees that Zoey is married to a wealthy museum owner he accuses her of being shallow and hypocritical. Zoey breaks down and cries, but only to get Ted's sympathy and record him saying something embarrassing. Zoey's husband comments on how overbearing Zoey can be sometimes, but Ted tells him that he thinks there's more to Zoey than that. Zoey overhears and feels the same.
Zoey winds up becoming friends with the rest of the gang, much to Ted's chagrin. When they all spend Thanksgiving together, Ted finds out that Zoey is a stepmother who feels isolated by her stepdaughter. Zoey and Ted decide to be friends, but when Ted sees Zoey call her husband and flat-out lie to him, Ted suspects that she might have feelings for him. Ted later finds out that Zoey has divorced her husband and they finally give in to their romantic feelings for each other.
Ted and Zoey's relationship is strained. They spend most of their time together arguing, but Ted feels like it keeps them from getting complacent. After talking it out with Lily, Ted realises just how tiresome it can be dating someone who doesn't support him. He's about to break up with Zoey, but deludes himself into believing that he's just taking Zoey for granted. Eventually Ted realises that he can't make his architectural dream a reality and still be with Zoey, so he breaks up with her and demolishes the Arcadian.
Some time later, Ted is tempted to get back with Zoey, but this never comes to pass. This relationship makes Ted feel too emotionally drained to try meeting new women and he eventually tries to get back with Robin.