Theodore Evelyn "Ted" Mosby (born April 25, 1978) is the main character, In 2030, Ted sat down to tell his kids the story of "How I Met Your Mother". Beginning in 2005, Ted's meandering journey has taken him through many failed relationships, including being left at the altar. But the architect-turned-professor isn't giving up on his search for the perfect woman. She's out there, and each episode of Ted's life brings him one step closer to meeting her.

Ted was born in Shaker Heights, Ohio. Ted can be easily described as a hopeless romantic, being a strong believer in destiny and constantly searches for his soul mate believing that fate will eventually cause their meeting. This has led to Ted believing that most of the women he has had relationships with could be "The One" and this has also led to many failed relationships, perhaps his most notable one being with Robin.

Ted's belief in finding "The One" can often come across as being hopeless and even idiotic. He has believed that most women he has gone out with he was destined to be with while almost every single one, led to bitter disappointment yet he never seems to learn from these mistakes. He always goes into a relationship full of optimism that this one will be different than the last only to have this belief destroyed and crushed. These constant attempts to find "The One" for him often result in the annoyance of the rest of the group and can make Ted look incredibly stupid. For example, in the case of Jeanette Peterson, Ted constantly tried to justify the woman's blatent attempts of stalking him as being romantic, a fact everyone told him was obviously false.

Ted and Marshall met at Wesleyan University, where they were roommates. After they graduated from Wesleyan, they rented an apartment together in New York. They lived together till 2008, when Marshall and Lily bought an apartment together. Ted repeatedly says that Marshall is his best friend in front Barney which annoys him, because he sees himself as Ted's best friend.

Ted was the best man at Marshall's wedding, alongside Barney.

Barney and Ted are good friends. Although Marshall is Ted's best friend Barney calls Ted his best friend. After Barney slept with Robin, they stop being friends until both are in an accident. Ted calls Barney his brother. Ted often goes to Barney when he's single instead of Marshall due to Marshall being married.

Lily and Ted are good friends and met in college. Lily is married to Marshall, Ted's best friend. Lily often does things to sabotage Ted's relationships because she sees her and Marshall growing old with Ted and his future wife. Although they are friends, Ted took Marshall's side and held a grudge against Lily, calling her names after she leaves Marshall to go to San Francisco.

After an awkward date where Ted professed his love for Robin (Pilot), she decided it would be better if the two stayed friends instead (Purple Giraffe). Ted and Robin both developed feelings for each other but at different times. They would both reciprocate their feelings 8 months after they met and Ted and Robin got together. (Come On). The two feel madly in love and where perfect for each other. They both said "I Love You" They had great chemistry, after a year however, they realized they weren't meant to be and broke up (Something Blue). Things were awkward for a while, but they were able to cement their friendship eventually by having sex on last time. (Slapsgiving) When Ted got engaged to Stella, Robin revealed to Ted that she had feelings for him and not to marry Stella. Robin eventually moved in with Ted (Not a Father's Day). Their becomes even stronger eventually Robin sees Ted her best friend and Ted sees her as "the one" Later, Ted tells her that he loves her and she moves out. (No Pressure) Though Ted finally lets go of Robin on the day of her wedding to Barney, it is revealed in the series' finale that she and Barney got divorced. Robin develops feelings for Ted, Ted's wife dies and Ted's kids give him permission to be together with Robin, after their mother died six years earlier.