What Will macOS 10.15 Be Called: Mammoth, Monterey, Rincon, Skyline, or Something Else?

Following Apple's shift to California-themed names for its Mac operating systems with OS X Mavericks back in 2013, Apple appeared to take steps to protect a number of other California-related names by filing for trademarks under a series of shell companies intended to mask the true identity of the applicant.

macos 10 15 names
All told, we identified 19 trademarks that were applied for under six different companies that all appeared to be Apple shell companies. Several of these names, including Yosemite, Sierra, and Mojave, have been used by Apple, while others have yet to be put to use.

Over the years, the trademark review process has played out for all of these applications, with most being subject to some form of back-and-forth between the applicants and examiners involving various approvals, denials, and suspensions. Even for approvals, however, owners are required to submit proof of the trademarks being used in commerce. This Statement of Use can be submitted up to 36 months after trademark approval, as long as the applicant regularly requests successive 6-month extensions to the original 6-month submission period.

With over five years having passed since the trademarks were applied for, many have now been abandoned, either at some point during the review process or through failure to provide proof of commercial use following approval. In fact, of the original 19 names that were included in the trademark applications, all but four of them have been either used by Apple or abandoned, with the remaining live applications being Mammoth, Monterey, Rincon, and Skyline.

Perhaps the most interesting one is Mammoth, which is likely related to Mammoth Lakes and Mammoth Mountain, a popular area for skiing and hiking in the Sierra Nevada mountains.

Notably, the trademark application for Mammoth was just approved earlier this month after many years of delays and a suspension. It's seen quite a bit of activity over the past six months, with the applicant Yosemite Research LLC having made some changes to reactivate the suspended application and shifting the attorney of record on the application to be noted trademark attorney Glenn Gundersen, who has worked with Apple on a number of intellectual property issues in the past.

mammoth trademark
The U.S. Patent and Trademark Office granted the registration for Mammoth and published it for opposition in March. After receiving no opposition to the trademark registration, the Mammoth trademark was officially allowed earlier this month on May 7. It's certainly possible that the timing is a coincidence, especially since the activity appears to have been driven by deadlines set by the Patent and Trademark Office in its communications regarding the suspended application, but the fact that the trademark was approved just weeks ago after years of relative inaction certainly caught our attention.

Monterey, a historic city and popular vacation spot on the Pacific coast, has been one of the popular macOS name options among our readers, so many will be happy to hear that this one remains a possibility. The trademark was applied for by Asilomar Enterprises LLC in December 2013, but wasn't allowed until June 12, 2018. One extension to the Statement of Use requirement has been granted, and Asilomar will have until June 2021 to prove commercial use of the name, provided additional extensions are requested.

Rincon is a popular surfing area in Southern California, and a trademark on that term was applied for by Landmark Associates LLC. The trademark was allowed on August 2, 2016, and Landmark has applied for successive extensions for the Statement of Use, with the fifth and final extension having been granted in January of this year. As a result, Landmark has until August of this year to prove the Rincon name is actively being used, or else the trademark will be lost.

Finally, Skyline likely relates to the scenic Skyline Boulevard that largely follows the ridge of the Santa Cruz Mountains running south from San Francisco, and Antalos Apps LLC filed for a trademark on the name in December 2013. The trademark was allowed on March 20, 2018, and the second Statement of Use extension was granted on February 28 of this year. The owner will have until March 2021 to prove use of Skyline in commerce, provided all necessary extensions are requested.

So what will macOS 10.15 be called? Will it be one of these four, or something completely different? Apple has drawn from the original list of trademark applications the majority of the time over the past five releases, but has selected something new a couple of times. One of Apple's presumed shell companies applied for a trademark on the name El Cap, but Apple opted to go with the famous mountain's full name of El Capitan for OS X 10.11, while 2017's macOS 10.13 High Sierra was positioned as a refinement of the previous year's macOS Sierra.

Related Forum: macOS Catalina

Popular Stories

iCloud General Feature Redux

iPhone Users Who Pay for iCloud Storage Receive a New Perk

Thursday March 20, 2025 12:01 am PDT by
If you pay for iCloud storage on your iPhone, Apple has a new perk for you, at no additional cost. The new perk is the ability to create invitations in the Apple Invites app for the iPhone, which launched in the App Store last month. In the Apple Invites app, iCloud+ subscribers can create invitations for any occasion, such as birthday parties, graduations, baby showers, and more. Anyone ...
apple wallet drivers license feature iPhone 15 pro teal 1

Apple Says iPhone Driver's Licenses Coming to These 8 U.S. States, But Rollout Remains Slow

Wednesday March 19, 2025 6:55 am PDT by
In select U.S. states, residents can add their driver's license or state ID to the Wallet app on the iPhone and Apple Watch, providing a convenient and contactless way to display proof of identity or age at select airports and businesses, and in select apps. Unfortunately, this feature continues to roll out very slowly. It has been three and a half years since Apple first announced the...
Generic iOS 19 Feature Mock

iOS 19 Coming in June With These New Features

Thursday March 20, 2025 2:04 pm PDT by
While the first iOS 19 beta is still more than two months away, there are already plenty of rumors about the upcoming software update. Below, we recap the key iOS 19 rumors so far. visionOS-Like Design In January, the YouTube channel Front Page Tech revealed a redesigned Camera app that is allegedly planned for iOS 19. According to Front Page Tech host Jon Prosser, the Camera app...
Windows Vista

Apple Might Be Having Its Windows Vista Moment, Says Analyst

Thursday March 20, 2025 6:52 am PDT by
Is Apple experiencing a "Vista-like drift into systemically poor execution?" That was a question posed by well-known technology analyst Benedict Evans, in a recent blog post covering Apple's innovation and execution, or seemingly lack thereof as of late. He is referring to Microsoft's Windows Vista operating system, which was widely criticized when it launched in 2007 due to software bugs,...
iPhone 17 Air Fanned Feature

First iPhone 17 Air Case Has Camera Bar, Camera Control Button Cutouts

Wednesday March 19, 2025 5:29 am PDT by
Serial leaker Sonny Dickson today shared an image of what he claims is a first look at a third-party case for Apple's iPhone 17 Air. "If you didn’t know an Air was coming, you'd swear it was a Google Pixel case," he said. Case manufacturers often obtain design specifications of upcoming iPhone models before their release by collaborating with Apple through official partnerships or...
iPhone 17 Pro Render Front Page Tech

Latest iPhone 17 Pro Dummies Highlight Apple's New Part-Glass Design

Thursday March 20, 2025 5:27 am PDT by
Seasoned leaker Sonny Dickson has shared more dummy models of Apple's upcoming iPhone 17 series, with the latest lot revealing a noticeable shift in Apple's iPhone Pro model design that goes beyond the much-talked-about new rear camera bar. Dickson points out that the iPhone 17 Pro dummy models feature an outlined area on the back, beginning just below the camera module and extending to the...
iphone 16 pro ghost hand

Next Year's iPhone 18 Pro Already Rumored to Have Five New Features

Tuesday March 18, 2025 1:00 pm PDT by
While the iPhone 18 Pro models are still around a year and a half away from launching, there are already some early rumors about the devices. Below, we recap some key iPhone 18 Pro rumors so far. Under-Screen Face ID In April 2023, display industry analyst Ross Young shared a roadmap showing that iPhone 17 Pro models would feature under-display Face ID. In May 2024, however, Young said ...
Generic iOS 19 Feature Mock

iOS 19 and iOS 20 Must Include a Long List of Major Changes, EU Says

Wednesday March 19, 2025 10:26 am PDT by
The European Commission today announced a long list of changes that Apple is legally required to implement in future iOS 19 and iOS 20 updates. The announcement clarifies interoperability requirements that Apple is required to adhere to in the EU, under the Digital Markets Act, which has been fully enforced since March 2024. The changes will further open up the iPhone and its technologies to ...
airpods pro 2 gradient

AirPods Pro 3 Launch Now Just Months Away: Here's What We Know

Tuesday March 18, 2025 9:13 am PDT by
Despite being released over two years ago, Apple's AirPods Pro 2 continue to dominate the wireless earbud market. However, with the AirPods Pro 3 expected to launch in 2025, anyone thinking of buying Apple's premium earbuds may be wondering if the next generation is worth holding out for. Apart from their audio and noise-canceling performance, which are generally regarded as excellent for...

Top Rated Comments

oneMadRssn Avatar
76 months ago
Cat-names were so much cooler.
Score: 58 Votes (Like | Disagree)
Khedron Avatar
76 months ago
Who cares. I'll never use it. This is the one that arbitrarily makes all my "unoptimised" applications no longer work, right?
Score: 45 Votes (Like | Disagree)
macdos Avatar
76 months ago
MacOS 10.15 Death Valley
Score: 40 Votes (Like | Disagree)
4487549 Avatar
76 months ago
Joshua Tree (pre-loaded with a free album from U2)
Score: 32 Votes (Like | Disagree)
baconsandwich Avatar
76 months ago
Mammoth would be terrible naming. A huge beast, slow and not very agile. Also extinct.
Score: 30 Votes (Like | Disagree)
cthart Avatar
76 months ago
Just drop the "10" -- that bit never changes anyway. Just call it macOS 15. Stop using names. iOS doesn't have names. tvOS doesn't have names. watchOS doesn't have names.
Score: 25 Votes (Like | Disagree)