May is here, and that means it’s TV cancellation season. Broadcast TV networks this month will reveal most of their programming for the next year, and that means fans will inevitably see a few beloved shows get the axe (unless you’re a fan of The CW).

Some shows have already been renewed or canceled, but there are always a few on the bubble. Their fate hasn’t been confirmed yet, but there's reason for fans to be concerned. Low ratings always make viewers nervous about their favorite programs, and early renewals add to the tension. Many networks don’t make hits like “Grey’s Anatomy” or “NCIS” wait until May. Their new seasons were announced in the winter.

Not every show knows its future, though. These are the shows that fans should be worried about:

1. “Nashville” — The music biz-themed ABC drama suffers from low ratings (producers are hoping to boost them with guest stars like Kesha and Elton John ), but those might not be the only numbers that matter. Money is also made off the songs from each episode (which are sold on iTunes and Amazon) as well as a summer tour each year. Without having those numbers, it's hard to say how the show is doing financially. On the creative side, critics generally agree that the Season 4 isn’t as good as the early years, but if “Nashville” is renewed, Variety reports, “My So-Called Life” executive producers Marshall Herskovitz and Ed Zwick will step in as showrunners and try to breathe new life into the music drama.

2. “Marvel’s Agent Carter” — This ABC drama doesn’t have the audience that other Marvel properties enjoy, despite being a critical darling. The series, which follows Captain America’s ex Peggy Carter (Hayley Atwell), averaged just over 5 million viewers in the first season. The second-season ratings dropped by nearly half to only 2.68 million viewers, making it one of ABC’s lowest-rated scripted shows.

3. “CSI: Cyber” — The last remainder of the “CSI” franchise could soon be gone. Ratings are down about 2 million viewers from last year, leaving the CBS drama to average 6.15 million viewers in Season 2. Of those viewers, only 0.92 were in the important age 18-49 demographic. Adding further fuel to cancellation speculation, Ted Danson has already signed on for NBC’s new comedy, “Good Place,” but the show could continue without him.

4. “Supergirl” — It’s hard to say what will happen to CBS’ foray into the superhero genre. With an average of 7.68 million viewers throughout the first season, the ratings aren’t amazing, but they aren’t bad either. “We heard very positive things, unofficially, from [CBS CEO] Les Moonves,” executive producer Ali Adler told TVLine. “[CBS Entertainment President] Glenn Geller and [executive vice president of current programs] Bridget Wiley — they’ve all been very, very supportive. We’re definitely talking about what Season 2 looks like.” Despite the support, “Supergirl” is still the only DC Comics show that has yet to be renewed for next year (though it’s worth noting that “Supergirl” is the only DC show on CBS).

Supergirl Will Kara (Melissa Benoist) get to keep defending National City? That depends on if CBS renews “Supergirl” for Season 2. Photo: CBS

5. “Undateable” — The sitcom was praised for going live each week, but viewers still didn’t tune in. Ratings dropped by over 40 percent from last season, and just 2.7 million people tuned in each week. It’s NBC’s lowest-rated show that has yet to be canceled, so don’t expect it to stick around for long.

6. “Telenovela” — NBC was once the comedy juggernaut, but its sitcoms haven’t been clicking lately. Like “Undateable,” “Telenovela” has not captured a big audience. It is the second-lowest-rated show on NBC, with just 3.44 million viewers. It seems unlikely that the peacock network will keep Eva Longoria’s freshman sitcom on the schedule.

7. “Sleepy Hollow” — The supernatural drama has had a rough season. Not only did it lose leading lady Nicole Beharie, but more than 30 percent of viewers from last year left. With 3 million viewers tuning in, it isn’t Fox’s lowest rated show, but it’s not in great shape. Still, the show managed to retain the majority of Season 3 fans despite moving to Fridays midseason. A steady following on a notoriously low-rated night might lead Fox to renew the show.

All ratings are from Nielsen via TV Series Finale.