Theodosian raises £967k led by Fuel Ventures with D11Z Ventures
This article covers a pre-seed round on 16 October 2025 into Theodosian, a UK cybersecurity startup reinventing enterprise security with file-level encryption and compliance. The round raised £967k and was led by Fuel Ventures, with participation from D11Z Ventures.
What does Theodosian do?
Theodosian offers a file-level encryption and compliance platform that keeps protection attached to data wherever it travels. It provides granular permission controls, continuous verification and per-file compliance checks to protect enterprise data and support regulatory compliance.
Why is Theodosian useful?
Problem
Businesses face rising data breaches and strict regulations like DCC and CMMC that risk costly compliance failures. Existing security often fails to protect files as they move, leaving data unprotected and non-compliant.
Solution
Theodosian explains that it helps by encrypting files at the file level and keeping protection with data as it travels. It performs continuous verification, granular permissions and 20 to 30 per-file compliance checks for DCC and CMMC readiness.
How much did Theodosian raise?
Theodosian raised £967k ($1.3m) in a pre-seed round led by Fuel Ventures, alongside D11Z. Ventures and 1818 Venture Capital. This makes it the 43rd largest funding round in October 2025 (49 recorded). It stands 432nd for 2025 (521 total) in the Startupmag database, as of 16 October 2025.
For details on how Startupmag compiles its rankings, view our Methodology.
Who invested in Theodosian?
Key investors in the round included:
- Fuel Ventures: A UK early-stage venture capital firm that invests in technology-driven startups, particularly software and SaaS businesses.
- D11Z Ventures: A European venture firm focused on technology startups across sectors and stages.
- 1818 Venture Capital: An early-stage venture capital investor that backs technology companies across Europe.
- HEARTFELT_: An investment group supporting early-stage technology startups with a focus on product-led companies.
- Startup Wise Guys: An accelerator and seed-stage investor concentrating on B2B SaaS and early-stage tech startups in Europe.
- Group of high-profile angels: Angel investors with backgrounds in enterprise technology and cybersecurity.
In the funding announcement, Mark Pearson from Fuel Ventures said:
Theodosian is building the future of enterprise cybersecurity. Their unique approach embeds protection where it matters most, at the data level, while staying laser-focused on compliance.
The investor added that Fuel Ventures would back the team from day one.
If you're researching potential backers in this space:
- Explore our list of cyber security venture capital firms in the UK
- Browse our directory of cyber security angel investors in the UK
Who founded Theodosian?
Where is Theodosian based?
Theodosian is based in London, UK.
What sector is Theodosian in?
Theodosian operates in the cyber security sector. This sector protects computers, networks and data from theft, damage and unauthorised access. In plain terms, it helps organisations keep information safe.
Key trends and challenges in Cyber security:
Regulatory pressure
New standards like the UK DCC and US CMMC force stronger controls and create compliance deadlines.
Data-centric protection
Organisations increasingly use file-level encryption so protection travels with data across clouds and devices.
Workforce and skills gap
There is a shortage of certified professionals, such as CISSP holders, for complex security roles.
For a deeper look at innovation in this space, see the cyber security startups in the UK.
They've invested in Theodosian
Get to know these cyber security investors
| Investor | Sector | Stage | Activity | Team | Connect |
|---|---|---|---|---|---|
 Fuel Ventures | 71 investments investments | 5 contacts contacts | |||
 D11Z Ventures | 1 investment investment | more info | |||
 1818 Venture Capital | 9 investments investments | 2 contacts contacts | |||
 Heartfelt Capital (HEARTFELT_) | 6 investments investments | 7 contacts contacts | |||
 Startup Wise Guys | 4 investments investments | more info |
Click here for a full list of 7,526+ startup investors in the UK