Here are all the CPAN distributions that start with the letter U:

UAV-Pilot
UAV-Pilot-ARDrone
UAV-Pilot-ArdupilotProtocol
UAV-Pilot-SDL
UAV-Pilot-Video-Ffmpeg
UAV-Pilot-Wumpus
UAV-Pilot-Wumpus-Server
UAV-Pilot-WumpusRover
UAV-Pilot-WumpusRover-Server
ubertext
Ubic
Ubic-Service-Hypnotoad
Ubic-Service-InitScriptWrapper
Ubic-Service-Memcached
Ubic-Service-MongoDB
Ubic-Service-Plack
Ubic-Service-ServerStarter
Ubic-Service-Starman
Ubic-Service-ZooKeeper
Ubic-Watchdog-Notice
Ubigraph
Ubuntu-Releases
Ucam-Term
UCS-Map8
UCS-String
UDCode
UDDI
UDDI-Lite
Udev-FFI
udp_proxy
UDPM
UDPmsg
UDPServersAndClients
UDT-Simple
Ufal-MorphoDiTa
Ufal-NameTag
Ufal-Parsito
Ufal-UDPipe
ufo
ufs
UHC
uHTML
UI-Bowdlator-Filter
UI-Dialog
UI-Dialog-Util-MenuControl
UI-KeyboardLayout
UI-Notify-Cocoa
UI-Various
UID
UID2-Client
UID2-Client-XS
Ujumla
UK-Vehicle
Ukigumo
Ukigumo-Agent
Ukigumo-Client
Ukigumo-Common
Ukigumo-Server
UkrMoney-API
UltraDNS
Umask-Local
UML-Class-Simple
UML-PlantUML-Encoder
UML-Sequence
UML-State
umlmgr
UMLS-Association
UMLS-Interface
UMLS-Norm
UMLS-SenseRelate
UMLS-Similarity
UMMF
Unamerican-Truth
UnazuSan
unconstant
uncpan
underscore
UnderscoreJS
Unexpected
uni-perl
Uni63
Unicode
Unicode-BiDiRule
Unicode-Block
Unicode-Block-Ascii
Unicode-Block-List
Unicode-CaseFold
Unicode-Casing
Unicode-Char
Unicode-CharWidth
Unicode-CheckUTF8
Unicode-CheckUTF8-PP
Unicode-Collate
Unicode-Collate-Standard-V3_1_1
Unicode-Confuse
Unicode-Debug
Unicode-Decompose
Unicode-Diacritic-Strip
Unicode-Digits
Unicode-EastAsianWidth
Unicode-EastAsianWidth-Detect
Unicode-Emoji-E4U
Unicode-Escape
Unicode-Fraction
Unicode-Homoglyph
Unicode-Homoglyph-Replace
Unicode-ICU
Unicode-ICU-Collator
Unicode-IMAPUtf7
Unicode-Indic
Unicode-Japanese
Unicode-LineBreak
Unicode-Lite
Unicode-Map
Unicode-Map8
Unicode-MapUTF8
Unicode-Normalize
Unicode-Number
Unicode-Overload
Unicode-Peek
Unicode-Precis
Unicode-Precis-Preparation
Unicode-Properties
Unicode-Property-XS
Unicode-RecursiveDowngrade
Unicode-Regex-Set
Unicode-Security
Unicode-Semantics
Unicode-SetAutomaton
Unicode-String
Unicode-Stringprep
Unicode-Strng
Unicode-Subscript
Unicode-Support
Unicode-Transform
Unicode-Transliterate
Unicode-Truncate
Unicode-Tussle
Unicode-Unihan
Unicode-UTF8
Unicode-UTF8-Parser
Unicode-UTF8simple
Unicode-Util
Unicode-Wrap
UnicodeOperators
UnicodeString
Unicorn-Manager
UnicornEngine
Unicruft
unicruft-perl
Uniden-BC75XLT
Unidexer
UniEvent
UniEvent-HTTP
UniEvent-HTTP-Manager
UniEvent-Socks
UniEvent-WebSocket
unigreek
UniLog
uniname-words
Uninets-Check
Uninets-Check-Modules-HTTP
Uninets-Check-Modules-MongoDB
Uninets-Check-Modules-Redis
uninit
Uniq
Unique
UniqueColumns
Unisyn-Parse
Unit-Duration
Unit-Simple
Units
Units-Length
UNIVERSAL
UNIVERSAL-Acme
UNIVERSAL-AUTHORITY
UNIVERSAL-AUTHORITY-Lexical
UNIVERSAL-can
UNIVERSAL-canAUTOLOAD
UNIVERSAL-cant
UNIVERSAL-derived_classes
UNIVERSAL-DOES
UNIVERSAL-dump
Universal-errno
UNIVERSAL-exports
UNIVERSAL-filename
UNIVERSAL-has
UNIVERSAL-implant
UNIVERSAL-isa
UNIVERSAL-moniker
UNIVERSAL-new
UNIVERSAL-Object
UNIVERSAL-ref
UNIVERSAL-require
UNIVERSAL-source_location_for
UNIVERSAL-to_json
UNIVERSAL-to_yaml
Universal-Version
UNIVERSAL-which
Universe-Galaxy
Unix
UNIX-Cal
Unix-Conf
Unix-Conf-Bind8
Unix-ConfigFile
Unix-errno
Unix-Getrusage
Unix-Groups
Unix-Groups-FFI
Unix-Login
Unix-Lsof
Unix-Mgt
Unix-Mknod
Unix-MyPathToInc
Unix-OpenBSD-Random
Unix-Passwd-File
Unix-PasswdFile
Unix-PasswdFileOps
Unix-PID
Unix-PID-Tiny
Unix-Pledge
UNIX-Privileges
Unix-Process
Unix-Processors
Unix-ResUID
Unix-SavedIDs
Unix-ScriptUtil
Unix-SearchPathGuess
Unix-setuid
Unix-Shebang
Unix-Statgrab
Unix-Sudo
Unix-Sysexits
Unix-Syslog
Unix-Uptime
Unix-Whereis
unix2dos
Unixish
UnixODBC
unknown
Unknown-Values
UNLbeautifier
unless
UNLreport
unpgphtml
unprint
UnQLite
UnRTF
Untaint
Untappd-API
Unwind-Protect
Unwire
uny2k
Unzip-Passwd
Unzip-Password
update
Update-Immutable
upfiles
uplug-cs
uplug-da
uplug-de
uplug-en
uplug-fr
uplug-hu
uplug-main
uplug-pt
uplug-ru
uplug-sl
uplug-sv
uplug-treetagger
UPnP
Upp-Reader
UPS-Nut
UPS.pm
UPSShipping
Uptake
UR
UR-Bundle
UR-Object-Command-Crud
URBL-Prepare
uri
URI-Amazon-APA
URI-amqp
URI-Based
URI-BNode
URI-Bookmarks
URI-Builder
URI-chrome
URI-Collection
URI-Coralize
URI-cpan
URI-CrawlableHash
URI-crid
URI-db
URI-di
URI-Dispatch
URI-duri
URI-Encode
URI-Encode-XS
URI-Escape-Any
URI-Escape-JavaScript
URI-Escape-Path
URI-Escape-XS
URI-fasp
URI-Fast
URI-Fetch
URI-Fetch-SimpleCache
URI-FetchFile
URI-Find
URI-Find-Delimited
URI-Find-Iterator
URI-Find-Rule
URI-Find-Schemeless-Stricter
URI-Find-Simple
URI-Find-UTF8
URI-Find-UTF8-ExtraCharacters
URI-FromHash
URI-ftpes
URI-ftps
URI-geo
URI-git
URI-GoogleChart
URI-http-Dump
URI-imap
URI-imaps
URI-ImpliedBase
URI-Info
URI-jar
URI-magnet
URI-Match
URI-mid
URI-NamespaceMap
URI-Nested
URI-ni
URI-Normalize
URI-OpenURL
URI-pack
URI-PackageURL
URI-ParseSearchString
URI-ParseSearchString-More
URI-PathAbstract
URI-Platonic
URI-Pure
URI-Query
URI-Query-FromHash
URI-redis
URI-Router
URI-s3
URI-scp
URI-Sequin
URI-sftp
URI-Signature-Tiny
URI-Simple
URI-SmartURI
URI-tag
URI-tcp
URI-tel
URI-Template
URI-Template-Restrict
URI-Title
URI-Title-iTMS
URI-ToDisk
URI-Unredirect
URI-URL
URI-URL-AddQueryParam
URI-urn-uuid
URI-UTF8-Punycode
URI-ws
URI-ws_Punix
URI-XS
URI-XSEscape
URIC
urifind
url
URL-Builder
URL-Check
URL-Checkout
URL-Encode
URL-Encode-XS
URL-Exists
URL-Find
URL-Google-GURL
URL-Grab
URL-List
URL-Normalize
URL-RegexMatching
URL-Search
URL-Signature
URL-Signature-Google-Maps-API
URL-Social
URL-Transform
URL-XS
Urlader
URLprocessor
URN-OASIS-SAML2
URPM
urpmi
US_DOD-STD2167A
uSAC-MIME
Usage
Usage-Sub
USB-Descriptor
USB-LibUSB
USB-TMC
USCIS-Case
use
User
User-AccountChecker
User-Config
User-Config-DB-DBIC
User-Config-DB-Keyed
User-Config-DB-Ldap
User-Config-UI-HTMLFormHandler
User-getgrouplist
User-grent
User-Identity
User-pwent
User-Simple
User-Utmp
UserAgentString-Parser
UserDB
Usergrid-Client
USPS-RateRequest
usw
Uta-Base
Uta-Dispatch-Base
Uta-Validator
UTF2
utf8-all
UTF8-R2
UTF8BOM
Util
Util-Any
Util-AsyncIO-RW
Util-CommandLine
Util-DataThing
Util-EvalSnippet
Util-Getopt-Menu
Util-H2O
Util-H2O-More
Util-IO
Util-LockFile-PID
Util-LockFile-Time
Util-Logger
Util-Medley
Util-Menu
Util-Properties
Util-SelfDestruct
Util-SQLiteDB-UniSchema
Util-Task
Util-Thread-Logger
Util-Timeout
Util-Underscore
Util-User
Util-User-Switch
Util-Utl
Util-Uuencode
Util-XML_YAML_Perl
Utils
utils_mail
UTM5-URFAClient
UTM5-URFAClient-Daemon
Uttu
Uttu-Framework-Uttu
UUID
UUID-FFI
UUID-Generator-PurePerl
UUID-Object
UUID-Random
UUID-Random-Patch-UseMRS
UUID-Random-PERLANCAR
UUID-Random-Secure
UUID-Tiny
UUID-Tiny-Patch-UseMRS
UUID-URandom
UUID4-Tiny
UV
UV-Util
UWO-Directory-Student
UWO-Student
UWP
Uzu