Luke Smith: Sarah Jane Smith's adopted son in The Sarah Jane Adventures. Grown from DNA by the Bane, he's not fully human and would be a big target for aliens on his own. He shared adventures with Sarah Jane and his mates, Maria Jackson, Clyde Langer and Rani Chandra in the spin-off show, which was sadly canceled after the untimely death of Elizabeth Sladen. He has the brain of a million humans and K9, his trusty robot dog to guide him through college. He'd be carrying on his mum's legacy and perhaps we'd see the Bannerman Road gang make a reappearance.

Rose Tyler and the Metacrisis Doctor, created by Donna Noble, were forced to a parallel universe on the Doctor Who Season 4 episode "Journey's End." This version of the Doctor committed genocide against the DALEKS, and the real Doctor wants Rose to help him learn compassion. He's human and will age at the same time as her. Roses' family also lives in the alternate universe, and her mother just had a son. From growing a TARDIS to fighting cybermen, the possibilities are endless! They may even join parallel Torchwood.

Jo Grant traveled with the 3rd Doctor in classic Doctor Who and made a return on The Sarah Jane Adventures episode "The Death of the Doctor." She was originally an assistant, given the job of looking after the Doctor by the Brigadier. Her memories of traveling the world helped save the day on The Sarah Jane Adventures, overloading the system the Sanseeth were using to create a TARDIS key through Sarah Jane and Jo's memories. Through this, they could control the blue box. During her travels, she also promotes humanitarian and ecological rights. Jo ended up married to Cliff Jones and had seven children. She even traveled down the Amazon River in a tea chest!

Let's be real, Donna Noble deserved a better ending. After helping save the universe on the Doctor Who Season 4 episode "Journey's End," towing the Earth back home and becoming part Time Lady, the Doctordonna was forced to have her mind wiped because the power was killing her. The DoctorDonna may have had her memories erased, but if she had lived, she would have made an amazing TARDIS team with the 10th Doctor. She'd be able to keep up with him with her superhuman brain and the Doctor would have his best mate at his side. With powerful aliens and comedy every week, it would be a guilty pleasure like tv shows human Donna enjoyed.

The self-proclaimed queen of evil has a difficult relationship with the Doctor, childhood best friends turned best enemies. The spin-off would tell us how the Master became Missy and escaped the Time War, which was never shown on screen. The last we saw of the Master was after his future self, Missy, killed him and he was sent down in the lift on the Doctor Who episode "The Doctor Falls." It would explain how he escaped the burning ship and ended up on Gallifrey. It would show how she turned from ruthless killer to having compassion for the Doctor. Missy also has unfinished business with Rassillon, leader of the Time Lords, and may run into her past self again.

Mickey Smith was originally Rose Tyler's boyfriend in Series 1, but joined Team TARDIS in Doctor Who Series 2 after a suggestion from Sarah Jane Smith. He stayed in Pete's Parallel world for a while in Doctor Who Series 2 and joined a cyberman fighting gang after his counterpart Rickey was killed. We're sure he helped Rose's father learn to care for his parallel daughter, and took care of his grandmother when he wasn't going in guns blazing on the old Torchwood.

Mother and Father of River Song, Amy and Rory were sent to Earth for a period of time by the 11th Doctor in hopes they might live. This was between Doctor Who Series 6 and 7, and covered an important gap in time that saw Amy become a model and eventually led to a falling out between her and Rory. A short from the BBC titled "Pond Life" saw them befriending an Ood, frequent phone calls from their son in law and occasional visits from River. Spin-off material, we think.

Susan Foreman traveled with the 1st Doctor and swept her school teachers Ian and Barbara Chesterton into their adventures. She's the Doctor's granddaughter from his first marriage on Gallifrey, and stole a TARDIS with him to explore the universe. After she fell in love with a human, the Doctor left her behind to find her own life. We can picture new companions of the Doctor going to her for a cuppa tea and advice. Sarah Jane definitely knows of her on The Sarah Jane Adventures.

The noblest Romana of them all, so much she traveled with the Doctor twice! Some fans even suspected a romantic relationship between her and the Doctor; Lalla Ward and Tom Baker were married on set for a while. After Mary Tamm regenerated into Lalla Ward, Romana was sent to E Space, a dimension outside our own with a green tint, with K9 by choice. Unaired adventures between her and the Doctor such as "Shada" or her journey to become president of Gallifrey in the Big Finish audios would be interesting to see.

Jenny is the Doctor's daughter, born from a stolen tissue sample on the planet Messalaine. She's engineered to be the perfect soldier and was thought to have died on the Doctor Who episode "The Doctor's Daughter." However, we see her stealing a ship and flying away after the Doctor leaves. She would explore the universe as she was born yesterday, and get to know herself as a part Time Lady! Big Finish audios have a series for her called Jenny starring Georgia Moffet, and it's well worth a listen.

Harriet Jones battled Slitheen with the 9th Doctor on the Doctor Who episodes "Aliens of London/The End of the World" and protected Rose Tyler, gaining his admiration. She runs for Prime Minister and leads Britain into its golden age. When she destroys the Sycorax on the Doctor Who episode "The Christmas Invasion" because she wasn't able to stop her men from being killed, the Doctor ends her career with the simple whisper of 'don't you think she looks tired?' Harold Saxon (the Master) takes over from her, but the spin-off would show the politics of the take over and if it was willingly...or through possession.

Brigadier Lethbridge Stewart was one of the first companions of Classic Doctor Who. He went on to have a daughter called Kate Stewart and she took over UNIT after him. The show would be her growing up and learning the ways of alien-fighting, with lots of stories about the Doctor from her father. She'd later create the Black Archives, an alien weapon storage of which the Doctor doesn't approve. Kate Stewart has appeared in many Big Finish audios about UNIT, which show the alien-fighting troops dealing with the Master.

The Ultimate Doctor fangirl, Petronella Osgood often cosplayed as her hero with bowties or question marks. (We won't say where.) In her first episode, The Day of the Doctor, the Zygons almost took over the world but the Doctor forced them to create a peace treaty with UNIT. This treaty involved the Osgood boxes, which threatened to destroy both races but really contained nothing inside. Only Osgood and her Zygon counterpart knew they didn't contain anything. The show would have the creation of the boxes and her acceptance of her Zygon sister. Osgood also appears in several Big Finish audio stories with Kate Stewart.

This Australian companion of the Fifth Doctor wanted nothing more than to be an air hostess. She was on her way to Heathrow Airport to become one when the Master whisked her away to join the Doctor's adventures and shrunk her aunt to death. BBC released a hilarious short about Tegan finally getting her dream job and telling us about the 5th Doctor DVD Box Sets. The spin-off would show her journey to becoming a flight attendant, perhaps even an air pilot one day after she left the Doctor on her own accord.

Captain Jack and River Song are the biggest flirts in the universe and would be perfect for each other if they had a spin-off. Both immortal, which caused indifferently by the Doctor, Captain Jack will eventually become the Face of Boe and River was destined to kill the Doctor. Captain Jack appears on the upcoming 6th Doctor Big Finish series with Trinity Wells, an American Newscaster, and had a spin-off show called Torchwood. River Song has her own Big Finish series called The Diaries of River Song. We're sure these two crossed paths, compared notes of The Doctor and never ran out of innuendoes. After all, they both encountered the Church of the Papal Mainframe and the Silence. Sorry, what were we talking about?

Sally Sparrow was a one-off companion on Doctor Who Season 3. "Blink" has a reputation for hooking new Doctor Who fans to the show, as its a mystery about time travel and features the iconic Weeping Angels. The statues that send you back in time and kill you if you blink. Sally loved to investigate old buildings, which was how she got wrapped up with the stone assassins. The show would perhaps have her join the police to investigate in more mysteries with her sort-of boyfriend Larry while they run their DVD shop, Sparrow and Nightingale.

On Doctor Who Season 7, we fell in love with the Paternoster Gang, aka Madame Vastra, Jenny Flint and Strax. An odder combination couldn’t be found elsewhere, as they’re a lizard from the dawn of time (Silurian) human and Sontaran. Jenny and Madame Vastra are married and solve mysteries in the Victorian era with Strax. While the Doctor was mourning the death of Amy and Rory Pond, he hid the TARDIS on a cloud in their time period and they looked after him. They’ve also had run-ins with Clara Oswald and River Song, frequent time travelers, and helped the 12th Doctor defeat the Clockwork Men after his regeneration. Strax has a bit of trouble telling when not to use weapons but the Sontaran is unique from his race as he grows to care for humans. Their spin-off would be a Sherlock Holmes-style murder mystery scope in Victorian London, with the most equipped detective trio London has ever seen. Aliens and human monsters lurking around dark London alleyways are no match for them. Big Finish Audio recently did a spin-off called the Paternoster Gang, which is a delightfully charming take on the trio.