How to Audition for a Co-Star Role on TV

The email comes in on a Tuesday afternoon. A network procedural, a co-star role, tape due Thursday. You open the sides: one page, three lines. You’re a nurse. You tell the lead detective that the patient woke up an hour ago and asked for her daughter.

Your first thought is relief: three lines, easy. Your second, a few hours later, is panic. How do you show anyone you can act in three lines? Do you make a big choice so you stand out, or play it plain so you don’t get in the way?

The short version: a co-star role exists to do a job in the story, usually to give the lead information, get in their way, or show what kind of world they’re in. Work out that job first. Then make one small, specific choice about how your character feels in this moment, play it as someone who is good at their work, and leave the spotlight on the lead. Be off book, read the whole script if you can get it, and treat your first tape as your only one.

What a co-star role is (and isn’t)

On a TV credit list, roles come in tiers: series regular, recurring, guest star, and co-star. A co-star is the smallest credited speaking part. A New York Women in Film & Television panel on first co-star jobs described it as a credited role, generally with a line or two. The same panel noted that the label often has more to do with a show’s budget than with the size of the part.

A guest star is a step up. As Backstage’s guide to guest roles explains, a guest star usually has several scenes in an episode, often with a story of their own, and tends to get higher billing.

You’ll also hear “under-five” (a very small speaking part, a term used mostly in daytime and network TV) and “day player.” The day-player label is used loosely: some people mean an actor with a single scene, others mean a co-star. Don’t worry about the vocabulary. If the breakdown says co-star, expect a short scene, a handful of lines at most, and a character defined by what they do.

Why three lines are harder than they look

It’s tempting to think a tiny part takes tiny preparation. Casting director Bernard Telsey says the opposite. In a Backstage report on a Drama League talk, Telsey, of Telsey + Company, called three-line parts the hardest to cast, and said he still wants an actor to come in with a take on the role.

The reason is simple arithmetic. In a long scene, an actor has pages to warm up, find the rhythm, and recover from a shaky start. In three lines you have only a few seconds, and every one of them shows.

There’s a practical reason, too. TV casting moves fast. Acting coach Topher Keene describes co-stars as the smallest tier, usually cast from self-tapes within days, often from a single read. A guest star might get a callback or a producer session. A co-star often doesn’t. So your first tape is often your only tape. Make it the finished version, not a sketch.

Find the job, then the function

Most co-star characters are at work. They’re nurses, officers, clerks, bartenders, lawyers, receptionists. That’s your first clue, and it’s a useful one.

Acting Studio Chicago describes these as roles that serve a function in the story. Its advice: work out why the character is in the script, and play them as competent at their job. A character who clearly can’t do the work draws attention, and attention is exactly what the scene doesn’t need from you.

So ask two questions before you rehearse a word.

1. What is my character’s job? Not just the title, but what doing it well looks like in this moment. An ICU nurse at the end of a twelve-hour shift moves and speaks differently from a hotel concierge on a quiet afternoon.
2. What is this scene’s function? Usually it’s one of a few things: you give the lead information, you block the lead from something, or you show the audience what kind of world the lead is in. Name it in a sentence.

Once you know the function, line readings tend to sort themselves out. If your job is to give the detective a key fact, the fact has to land clearly. If your job is to be an obstacle, you need a real reason not to let the lead through.

Read the whole script, and watch the show

Sides are a few pages cut from an episode. They rarely tell you what just happened, or why your three lines matter. Casting director Marci Liroff makes the point in Backstage: read the whole script for a film or TV role, she says, “whether you’re coming in for one line or 20.” If you can’t get it, ask your agent, or ask the casting office politely.

Then study the show. SAG-AFTRA’s self-tape guide tells actors to research beyond the sides: the show’s tone and pace, and the earlier work of its producers and director. Watch at least one episode, ideally one with a small role like yours.

Pay attention to how the small speaking roles in that episode behave. A fast procedural and a multi-camera sitcom ask for very different energy and timing, and the small parts follow the show’s lead. Your three lines have to sound as if they belong to that show, not to a different one.

Our guide to breaking down audition sides walks through the rest of the homework: what happened before the scene, who your character is talking to, and what they want.

Make one choice, not five

Here’s where coaches disagree, and it’s worth knowing both sides. Actor Adrian Martinez, in an interview with Casting Networks, recommends treating a small part like a lead and building a backstory even for a bit role. Atkins Estimond, writing for Catapult Acting Studios about his own co-star audition, argues that a co-star’s job is to keep the story moving without pulling focus, and that you can skip the elaborate backstory and objectives you’d build for a lead.

A middle path works for most actors. Do enough private work to know who you are and what this moment means to you. Then turn it into one playable choice that the camera can see, and stop there.

Good co-star choices are small and specific:

• The nurse likes this patient and is quietly relieved she woke up.
• The desk clerk has been told not to talk to police and is deciding how much to say.
• The bartender has seen this kind of trouble before and wants the detective gone before it starts.

Each one colors the lines without adding anything to them. What a good choice never does is change the words, add a pause long enough to slow the scene, or invent a bit of business that pulls the eye. Actor Jim Garrity, in a Casting Networks piece on working your first co-star role, said a co-star part doesn’t leave much room for interpretation. The choice lives inside the lines, not on top of them.

Serve the lead without disappearing

“Don’t pull focus” doesn’t mean “be bland.” It means the scene is about the lead’s story, and you help tell it.

Coach Matt Newton gives a useful rule for screen scenes in Backstage: “Your first line is always a response.” Scenes on screen usually start in the middle, so your first line answers something, even if that something happened off the page. Know what it is, and your line will sound like part of a conversation rather than a reading.

Three habits keep you in the scene without taking it over.

1. Listen to the reader. Your character is reacting to the lead, so let the reader’s line actually reach you before you answer.
2. Stay in it after your last line. The camera may hold on you while the lead reacts. Keep thinking as the character until the scene is clearly over.
3. Keep it to the size of the frame. Frame yourself fairly tight, the way a TV close shot would. Our guide to acting for shot sizes explains how much a close frame picks up.

Taping the co-star audition

Most co-star auditions now start as self-tapes. SAG-AFTRA’s self-tape rules, as Backstage explained them under the 2023 agreement, require that you get sides at least 48 hours before the deadline (72 for minors), cap a first self-tape at 8 pages, and don’t require you to memorize. Under the 2026 TV/Theatrical agreement, producers also can’t charge you to submit a self-tape. Rules change, so check the current ones if you’re unsure.

Memorizing isn’t required, but with three lines there’s no reason not to. Being off book frees your eyes for the reader and lets you listen. Here’s a simple run-up for a 48-hour turnaround.

1. Hour one: read the sides, then the whole script if you have it. Name the character’s job and the scene’s function in one sentence each.
2. Same evening: watch an episode for tone and pace. Pick your one choice.
3. Next morning: learn the lines with their cues. Know the line before each of yours as well as your own, because that’s what you’re answering.
4. Next afternoon: tape three or four takes with a reader off camera, close to the lens. Send your best one, plus a second take only if it’s genuinely different and the casting notes allow it.

For framing, eyeline, and sound, see our guides to self-taping alone and slating for a self-tape.

Getting the lines solid when there’s no one to read with

The awkward part of a co-star tape is that the lines are easy and the cues are not. You need to hear the lead’s line and answer it, and on a Tuesday night there may be nobody around to say it.

Offbook can help you drill that exchange. Upload the sides, pick your role, and realistic voices read every other character, while Offbook listens through your microphone and plays the next cue when it detects you’ve finished your line. Hide your own lines so you’re answering from memory, and run the scene until the response feels like a reply rather than a recital.

Then tape it with a real reader, keep your one choice, and let the lead’s story be the story. A co-star who makes a scene work can stick in a casting office’s memory, and that can lead to the next audition.

Questions actors ask

Is a co-star role worth doing?

For most screen actors, yes. It’s a credited role on a TV show, it goes on your resume, and it puts you in front of a casting office that casts the show week after week. Our SAG-AFTRA eligibility guide explains how union jobs count toward joining.

Should I build a full backstory for a co-star?

Do enough to know who you are and what the moment means to you, then turn it into one specific choice. A full biography rarely shows up in three lines, and it can tempt you to add things the scene doesn’t need.

Can I change or add a line to make the part bigger?

Don’t. Jim Garrity notes that a co-star part leaves little room for interpretation. An added line or ad-lib in a tape can also read as not understanding what the scene needs from you. Put your creativity into how you say the lines, not which lines you say.

What if I only get one page of sides?

Ask your agent or the casting office whether the full script is available. If it isn’t, work from what you have: who you’re talking to, what just happened, and what your character’s job requires. Our guide on sides versus the full script covers what to prepare in each case.