HexChat
Chat with other people online
Konversation
Debug sources for package konversation
KVIrc
Connect to Internet Relay Chat

Loqui
IRC client

Polari
An Internet Relay Chat Client for GNOME
Quassel IRC (Client only)
Distributed IRC client with central core component
Quassel IRC
Distributed IRC client with central core component
Smuxi
Chat with other people on IRC

Weechat
Extensible chat client
TalkSoup
IRC Client for GNUstep

XChat-GNOME
Chat with people using IRC

LostIRC
Chat on IRC-networks
XChat
Chat with other people using Internet Relay Chat
CenterIM
Text-based Instant Messenging client

Riot
A feature-rich client for Matrix.org
irssi
irssi, the IRC client of the future
Srain
Modern IRC client written in GTK.